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As it is noticeable, there are several research projects with regard to using of cavitation and the production of bubbles for friction reduction in ship movements. I want to understand the mechanism thoroughly for this process. Also, how much is it practical for decreasing fuel consumption?
Best regards,
Hossein Pouresmaeil
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This is an inescapable fundamental review (one of the oldest but most quoted) on drag reduction by bubbles on an external flow; Whether injected or created using cavitating flows, the physical phenomenon is fundamentally the same: a dispersed gas-liquid flow that has often been tackled using two-fluid models.
Ceccio, S.L. (2010). Friction drag reduction of external flows with bubble and gas injection. Annual Review of Fluid Mechanics, 42, 183-203.
Abstract
The lubrication of external liquid flow with a bubbly mixture or gas layer has been the goal of engineers for many years, and this article presents the underlying principles and recent advances of this technology. It reviews the use of partial and super-cavities for drag reduction of axisymmetric moving objects within a liquid. Partial cavity flows can also be used to reduce the friction drag on the nominally two-dimensional portions of a horizontal surface, and the basic flow features of two-dimensional cavities are presented. Injection of gas can lead to the creation of a bubbly mixture near the flow surface that can significantly modify the flow within the turbulent boundary layer, and there have been significant advances in the understanding of the underlying physical process of drag reduction. Moreover, with sufficient gas flux, the bubbles flowing beneath a solid surface can coalesce to form a thin drag-reducing air layer. The current applications of these techniques to underwater vehicles and surface ships are discussed.
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https://www.researchgate.net/project/Ancient-Hydrological-Knowledge-and-Old-Hydraulic-Structures Can we share information about ancient hydrological knowledge, old hydraulic techniques, and ancestral water management methods
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The Central Bank of Tunisia (BCT) has put into circulation a new banknote of 5 dinars (type 2022) with a dimension of 143 mm x 73 mm, bearing the image of the engineer and left-wing activist and agricultural engineer , Slaheddin Amami (1936-1986); Tunisian agricultural engineer who had initiated the reform of the Tunisian hydrological system. He has made important contributions, in particular to the agricultural problems of arid and semi-arid zones, and more particularly, to the genius of local populations to adapt to them by developing ancestral knowledge on the management of water and soil resources, explaining the foundations of dryland farming in southern Mediterranean countries.
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I am doing a project related to screw turbine, in which I am supposed to analyze the screw rotation, when the flow speed of the water is 2m/s. For this I prepared a model in soldworks and use the ansys fluent to solve the governing equation. I used the dynamic mesh with cell height equal to my mesh size(0.05m). I used the transient analysis. The screw doesn't seem to rotate when studied in the cfd post.
Pardon me if the problem statement isn't clear. I am a beginner.
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I´m trying to get an optimal reservoir operation rule  in a multireservoir system where some reservoirs have carryover storage. I had developed an operation  model based on Kritski and Menkel´s method and uses generalized Storage - Reliabiliy-Yield relashionship. This model has been tasted and implemented in single reservoirs but not in a multireservoir system. I want to know if there are other  carryover storage methods that have been implemented in a multireservoir system.
Thank you.
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That is a good question.
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Hi
In some studies we need to calculate the main channel length/slope of a certain river.
For example you can see a real catchment in uploaded pic with it's main river and tributaries.
Now, I have some questions:
1. What is the definition of main stream channel of a river and how can we determine it using ArcGIS?
2. If you want to calculate the main channel length, In the appended pic, which one is your choice as the main channel (Black one or Red one?)
Can we suppose the longest channel stream as the main stream?
3. Is there any tool in ArcGIS to calculate the length and slope of stream channel?
Thanks
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It is a nonpresmatic channel having the longest river path, maximum discharge and bigest flood plains. Velocity and area field measurements are essential to the actual determine the discharge.
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Hello,
I am working on bigger project. The project includes many subbasins that have to be considered. We are working each on one subbasin at the time. Input is effective precipitation.
Our simplified workflow with SI units is:
1. Modelling terrain (.tiff) Terrain with coordinate system
2. Subbasin border (.shp) 2D Flow area base cell spacing (bigger)
3. Hec ras mapper
3.1 2D FLOW areas edit add breaklines for roads, railways, riverbeds. Adjust cell spacing (smaller). Enforce breaklines.
3.2 2D FLOW Refinement regions
4. Adding unsteady flow data Precipitation, Normal Depth as downstream boundary.
5. Running model Unsteady flow analysis with computation settings
6. The »right/validate« result is calculated.
And now comes the error. After opening Hec ras mapper to view result we get notification of »Error in Loading Geometry data« The geometry section of 2D Flow Areas gets red dot. Breaklines, refinement regions, boundary condition lines are lost. On the left down corner we get the error “ Fail to Load. Start Editing to Recompute Mesh”. This error has begin to appeared after the half of basins were done. Now even the finished subbasin are getting the same error. Did anybody encounter similar problem? What am i doing wrong? Any help is appreciated.
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Hello, I have the same problem with HEC RAS ​​V6.0.0; Beta 6.0 did not have the problem but final version 6.0.0 has a lot of bugs. it looks like Ras Mapper is not related to HEC RAS ​​that means if you create your geometry on ras mapper and set your boundary condition HEC RAS ​​cannot detect them. even if you restart HEC RAS, they will disappear. Hope they will fix this problem as soon as possible .
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it means the oil pump to be sometimes able to turn off during the driving cycle, and if it is possible, how efficient would it be? (more particularly in heavy vehicles like a bus).
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It depends upon the size of the accumulator, and the flowrate required. If you calculate the flowrate required for the PAS pump you could work out the accumulator volume required. See link below for typical (but a little old) energy consumption info.
However, many modern vehicles are moving to electric PAS systems, so the traditional hydraulic system may not be required in future.
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Dear Sir,
When we conduct a fixed bed hydraulic model for an actual river reach model, we have to set up the artificial roughness on the fixed bed such as bolt/nuts to be spaced scattered. In the propto type, of course, we have a roughness as the calibrated or designed values as manning values.
Are there some guideline (in English literature) on how to convert the manning roughness value to the artificial roughness parameters ?
Thank you
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Yes I have some paper my be interested for you
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What would be the implications of an unanticipated drastic rise in the water surface elevation in the inlet channel upstream of an inverted siphon with all the rest design parameters (e.g. discharge, downstream water elevation etc) remaining the same as considered in the original design? What kinds of malfunctions would affect the siphon's operation in that case?
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It is could be causes the flooding in the inlet structures of the inverted siphon as well as increasing the inlet velocity of the hydraulic structures.
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Currently, the combined effect of all clouds is one of net cooling, meaning that clouds are dampening the rate of climate warming. But scientists are looking into whether clouds will have the same effect on climate as the Earth continues to warm. If the proportion of different cloud types changes, it could affect the rate of climate change because different types of clouds have different impacts on the Earth's climate. While some types of clouds help to warm the Earth, others help to cool it?
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Well,
The answer can be found in the earth's energy budget as shown in the attached figure.
Regards
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Can anyone help direct me to papers or books about trash screen or debris mangment?
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Dear Researchers
According to your practical experience, which formula, out of the following three, is more reliable for calculating head loss in water supply pipes and provides better results when compared to the actual values?
Hagen–Poiseuille
Darcy–Weisbach
Hazen–Williams
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Dear Roland,
What you wrote is incorrect. This is not the right relationship for pressure drop.
Considering the Darcy-Weisbach formula, we can write that the head loss is :
dh= (fL/D)x(V^2)/2g
The pressure drop is then : dp = rhoxgxdh
That is : dp = rhoxfx L x('V^2)/(2D)
You can see that the constant g is simplified and does not intervene in the pressure drop according to the Darcy-Weisbach relation.
Regards
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Hi.. What is the best MATLAB text book that is most suitable and full of solved examples to teach students how to solve applications of thermal engineering using Simulink?
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a very good interesting question
what about FEM toolbox
it could be helpful???
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I need to simulate the transition of Flow through Coarse Porous Media such as Rock-fill dams, to investigation of Water level profile in each distance from up-stream and determination of discharge of fluid seepage from the body of these media. Notice, I want to simulate a Single-Phase Flow.
How can I simulate this project? Please suggest and introduce a useful software for this issue to me...
What is your idea about Flow 3D, Fluent, ABAQUS,...
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Dear Dr. Majid Heydari ,
It would be appreciated if you explain more about the method you used to simulate the POROUS MEDIA for your Ph.D. thesis.
Best regards,
Mehdi
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I designed a pneumatic motor( hydraulicmotor) in this field and I want to know what the problem is?
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Thank you John Machell
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In a 12-meter-long straight channel, a gate with a pneumatic jack has been employed at about a meter before the butterfly outlet gate (used for adjusting the water height) so that it would be used to generate positive surge. When the gate is closed suddenly (in about 0.2 second), it causes an increase in the flow depth and thus conversion of the flow from steady to unsteady, the fact which results in wave progress. I would like to know whether this type of positive surge resulting from sudden closure of the gate (whether with an approximately 2.5 cm opening, or with a complete closure) could be modeled in a straight channel using Flow3D? what software program may be used for its simulation?
Best regards,
Maryam Akbari
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(I did not understand the setup, it would be nice if you show a schematic in a figure, I assume it is a free surface flow with a gate and a wave generator and one end)
Surge* governing equations (water hammer equations) are special form of full 3D Navier-Stokes. They have the exact structure of 2D Saint Venant (SWE) and 2D Euler equations mathematically. Back to your question, yes you can model it with Flow3D, model 3D N-S equation with moving object module as a boundary and you wold capture the wave due to closure of the gate. If your problem is symmetric in the transverse direction you may solve it with 2D layered averaged N-S solver of Flow3D as well.
PS:
* Surge in the literature of pump and pipeline means "water hammer", it is not the "storm surge" in the literature of coastal engineering
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hello everyone!!
we often encounter with the partial differential terms. (partial)dy/dx.
i have shown the exact form of the equation in which i am interested in.
if i have the values of both the variables then how to estimate it.
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You can do it numerically as it is mentioned above. If it is a sharp changing function you have to use some numerical tricks. Those tricks can become very advanced up to a PhD level thesis. But as starting point fitting a spline locally and get the derivative of the spline at that point is a common practice.
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My work is mainly experiment-based research. Moving a step further in the advanced analysis, can you please help me with the following questions?
1- Do you think this topic is linked with dynamic systems analysis? if yes: how this analysis should be done?
2- What kind of theoretical analysis (based on differential equations formulation) could be added to my research (especially to the vortex's stability and/or stochastic factors)?
3- What's your best suggestion for making sure that the results obtained (from experiments) are dependable? (Validation by CFD?)
Every single answer is important to me.
Thank you very much.
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Vortex flows are ubiquitous at all scales of matter organization, from quantum systems to large structures of the universe. In the most general mathematical sense, it is useful to look at these structures in a unified way. When trying to organize my ideas in this field, I have encountered a book on the general theory of vortices that I recommend as a valuable source of information placing the subject in a multidisciplinary context; for the synopsis please see:
Regarding the research suggestions, I agree with the previous comments, but I can add some specific answers:
>>Do you think this topic is linked with dynamic systems analysis? if yes: how this analysis should be done?<<
The answer is definitely yes. You can consider the following paper as an illustration of the methods derived from Dynamical Systems Theory.
>>What kind of theoretical analysis (based on differential equations formulation) could be added to my research (especially to the vortex's stability and/or stochastic factors)?<<
The theory of stable and unstable manifolds discussed in the reference above. It is also useful to consult a book by Ottino: The kinematics of mixing: stretching, chaos and transport
>>What's your best suggestion for making sure that the results obtained (from experiments) are dependable? (Validation by CFD?)<<
The best way to obtain reliable results is to set an experiment as carefully as possible. CFD calculations are generally validated by experiment. However, the use of CFD to validate the experimental results is very useful (I always look at numerical simulations as a parallel experiment).
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In unsteady open channel flow of storm water networks of circular section, besides the hydrographs entering in each link resulting from the continuity equation and excluding weirs or control devices, frequently the boundary conditions considered are the energy equation in the manholes and the critical condition or the uniform flow condition in the case of a free fall downstream or manhole without influence from downstream. A possible approach that is sometimes considered in design situation considers each link separately and the condition of steady uniform flow in the downstream end of each link, for each flow rate reached in the extremity in any instant of time. What is (or may be) the magnitude of the differences reached with this approximation with respect to the real conditions, assuming, in any case, an open channel flow as should be considered in a design situation?
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Happy to read good points, but the magnitude of the differences reached with this approximation with respect to the real conditions further needs elaboration with examples.
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I require a constant water flow rate of 0.5 LPM/1LPM for my water disinfection system. The flow of water should be constant through out system. Is it possible to control water flow rate without using hydraulic pump?
Secondly, somebody suggest me to use water control valve for constant water flow rate. How can I choose water control valve suitable for my system?
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Pipes sometimes are classified as flexible or rigid pipes by checking the vertical deflection-to-internal diameter ratio in which the structural damage of the pipes subjected to parallel plate testing occurs. This control is made with unaided eyes. Do you know of any specific vertical deflection-to-internal diameter ratio associated with the beginning of the damage in which the flexible and rigid pipes are differentiated? Do you know any references for that classification?
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Thank you so much for your reply. I have found the answer of my question from your replies.
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hydraulic forging press of 400 ton capacity required how much quantity oil. all the other parameters are known.
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hi abdul,
there are basically three type of flows to consider,
- displacement flow = cylinder velocity times cylinder area
- compression flow = ammount of oil to raise pressure to force/cyl area required. the attached volume plays a crucial part here
- leackage flow = volumetric losses of drive train under pressure
sum of the above gives you the total required flow.
you can compute by hand or use a hydraulic simulator tool. bosch rexroth offeres one for free. check it out at www.boschrexroth.com/simster
good luck
m. liedhegener
bosch rexroth ag
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Hello everyone!!
I would like to know , How to convert hourly stream flow discharge to daily discharge ?
Please help
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The discharge data thats measured hourly in m3/s can be averaged over period of 24hrs ( average of 24 values) to report mean daily discharge in m3/s.
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I want to calculate the amount of seepage in an earthen dam where the slope is protected with vetiver against stable seepage slope failure. For this I want to know the coefficient of permeability of the soil sample at the slope which is rooted with vetiver. So is there any way to calculate the coefficient of permeability keeping vetiver alive?
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Immediately to my mind , it comes as why not to compare two comparable situations , one with vetivar roots and another without roots..
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AMC is the moisture condition of soil before 5 days actual rainfall.
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Antecedent Moisture Content means the preceding wetness condition of the area under study. Rainfall-dependent inflow and infiltration (RDII) into sewer systems is highly affected by antecedent moisture conditions . The travel paths for RDII entering the sewer system are very complex because the transport mechanisms include both surface runoff and subsurface transportation. This adds additional complexities to the hydrologic effects and antecedent moisture effects such as the saturation levels of the soils in the subsurface, groundwater levels, and subsurface hydraulics. Curve number is a coefficient that reduces total precipitation to runoff potential after losses. Therefore higher the CN value higher is the runn off potential.It is crucial to use CN value that best represents the ground cover type and hydro-logic condition
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Hai everyone, I am working of SWAT CUP for my validation and calibration. After doing first calibration , i got the value of NS equals -0.17. Then when i am again doing my calibration again to get the exact value of NS  , i am facing an issue that "the application has requested the run time to terminate in an unusual way ". i attached the screenshot of the problem what i am facing now.  Can anyone give a proper solution for this , so that i can move further. 
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My dear your program got a divergence. this is occurred when the errors summation is exaggerated, correspondingly the program terminates himself. This occasionally is occurred when the boundary conditions are not adjusted.
Please dear colleague give a correct value for every node at the boundary of your model domain and rerun the program again. if you do so, surely, the problem will be diminished.
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Hello every one!!
im looking for the trend of LULC. suppose there is change in Agricultural land then how can i find the trend of it? in the agricultural land, suppose there is particular type of crop cultivation is also changing, how can i capture that trend? in the same line, i'm wondering what would be the resolution of image required to see the changes in particular crop cultivation area?
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Hello Praveen,
First, you need time-series data (preferably remotely sensed images) to observe trends in LULC.
A good starting point in deciding the suitable image spatial resolution is to consider the landscape structure in terms of composition and spatial configuration.
And depending on the extent of your study area you may consider satellite or aerial images.
I assume you are familiar with your study area and have a fair idea about the rate of LULC changes. This will be vital in deciding the temporal resolution of the images (e.g seasonal, yearly, decadal etc.).
You can then apply supervised image classification methods and make area estimates of different LULC types (see FAO's OpenForis tool for area estimation) and analyze trends in LULC.
At the crop level, you may extract and test suitability of spectral (e.g. NDVI, EVI, spectral bands, tasseled cap variables etc.), textural (Homogeneity, entropy, variance etc.) and phenological (e.g. mean NDVI) variables from the remotely sensed images to characterize different crop types.
Select the most suitable variables and apply image differencing and thresholding methods.
Hope you find these useful.
Best regards,
Kwame
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Hello Everyone
im looking for the discretization tools or techniques or strategy which can be used in the matlab.
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Hi
There are Finite Element, Finite Volume and Finite Difference methods.
Also refer attached presentation for more info.
Recommend ans if found useful.
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I need an output discharge of various flow rates varying from 0.5 to 15 liters/minute at a constant pressure of around 0.7 bar; could you please suggest to me which type of pump can be used to achieve these conditions?
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No, we are now altering overhead pressure to vary the flow rate.
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Two plastic tubing are to be connected and glued in perpendicular for fluid flow. Can you suggest any tests that can be done to detect any leakage at the joint?
See attached photo.
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An efficient way to detect leaks is to fill the tubes with a tracer gas at the service pressure to analyze the air around the conection with a detector adapted to this gas. The reversse may also be done, putting the connection in a tight box filled with a tracer gas and analyze the gaz in the tube.
Possible tracer gases and detectors are
light hydrocarbons (methane ethane, etc.) and flame ionisation detector
halogenated gases with electron capture detector
CO2 or water vapour and infrared detectors
An obvious method to detect important leakages may also be usefull: fill the tube with air under pressure and put the connection under water. Bubles will appear at importantn leakages.
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I'm trying to find the discharge coefficient (Cd) for an orifice knowing the orifice diameter, the inner diameter of the tubing, and the flow coefficient provided by the manufacturer.
I've tried using the equation
Cv = Cd/sqrt(1-ß^4)
This however returns a number that makes no sense (less than 0.01). I'm expecting for my numbers something in the range of 0.7 to 0.85. Is that the wrong equation?
For example, I know for another orifice that Cd = 0.89, Cv = 0.025, ID = 0.2", orifice diam. = 0.01. That equation doesn't give the Cd I know from experimental data is true.
The orifice I'm trying to find Cd for has Cv = 0.028, ID = 0.20", and orifice diam. = 0.035"
Thanks for your help.
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Dear Stephen,
The equation is much more complicated. Use the Stolz equation that you will find in the following link.
With my best regards
Prof. Bachir ACHOUR
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give the method or formula to find the depth -averaged water flow velocity in a rectangular open channel.
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As a quick approximation, time a piece of floating material in the middle of the river for a distance of about 30 m or so.  Calculate velocity and multiply by 0.86.  This result was shown decades ago to be a good approximation to the log law and gives you a good estimate of the depth-averaged velocity.  
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We are working on a experimental set-up design to observe fracturing. For experiment we are in search of the best way to monitor the change in fracture width with pressure during fracturing.
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You can do so by using Gas Tracer Log.
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when I'm designing a hydraulic system, I wonder the tolerance
of shafts of the motor and pump.Is there an ISO doc tell it or some industrial tradition?
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check NEMA standards
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I'm trying to estimate groundwater recharge and I need specific yield to do that. I have read about method of using rainfall data and groundwater levels or linear regression of these two parameters but I do not understand this empirical technique 
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If your groundwater levels are shallow, you should look into these two recent papers (open access) that provide you suitable equations that correctly account for water retention in the unsaturated zone as well as the influence of the microrelief. The 2016 paper also describes how to derive van Genuchten parameters from water level rises after rain events.
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Hydraulic Cylinder 
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You will find commonly are fixed using nut for easiness of assembly and disassembly. If you intend to weld the rod with the piston,you have to ensure they are concentric.
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I am looking for a stochastic model in use clearly for extreme rainfall generation.
the rainfall will be used for hydraulic models and drainage system models.
few concepts are developed in past but it seems there is not any toolkit or software with manual about them, like 
Neyman-Scott (NS) or   Bartlett-Lewis or DRIP MODEL
thanks
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you can find a Matlab code implementing Neyman-Scott here on RG:
we can support you a bit...as we developed this code :)
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The moving part starts moving once the pump is started and before starting the test. 
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Sorry sir, I beg to differ from your opinion, the actuator is not supposed to have any displacement , unless desired . If any unwanted displacement is being observed, it may be faulty electrical signals (noise) , hydraulic parts  or machine settings.
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I am looking for a reference (book, paper...) where to find a clear explanation of the different techniques that can be used to implement boundary conditions  for 2D shallow water equations with a finite volume implementation. Can anybody help ? Thanks a lot in advance. Marco
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Hello,
No math...
First absolute rule :
  • Upstream (inflow) : subcritical : 1 condition; supercritical : 2 conditions
  • Downstream (outflow) : subcritical : 1 condition; supercritical : 0 condition
A "condition" is the value of a state variable (h, q).
The external state variable of a boundary border must be initialised whith the internal values, that is no condition.
Then, two possible implementations:
  • Hard : the flux of the border is directly computed from the external values
  • Soft : the flux of the border is computed with your favorite Riemann solver, considering the external values, eventually changed with your boundary conditions
Recommendations:
  • A boundary condition can be upstream, downstream, subcritical and supercritical during a single simulation !
  • The best thing to do with that, as a programmer, is to let the full responsability of the definition of the boundary conditions to the user. No check during simulation. No hypothesis in the code.
  • Think of a numerical model as a physical one! We need bassins, upstream and downstream, to impose physically boundary conditions! Create also bassins in your numerical models : your boundary conditions will becomme evident and stable.
  • Implements hard boundary condition : you wil retrive your imposed values in the result. Soft implentation is also correct, but more complicated to communicate to the client...
Best regards,
Dr Jerome Dubois
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For lifting of objects on the seabed, one must to overcome the mud suction force to allow the object to be lifted. The loads will be immense if pulled instantly. The question is how an initial estimation of breakout force can be made.
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The attached paper might help you in computations. 
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Can anyone help me about hydraulic shaft seal testing procedure? I want to test seals in an accelerated stress condition to expedite the test. Is there any standard equipment available to test seals at higher temperature, pressure, and velocity?
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Ohhh!!! que bueno encontrarte, Joel! (tu no tienes ni un pelo de zonzo, ja, ja).
Como bien señalas el gran "pulmon" regional del agua está en los acuíferos que tenemos aquí, El Guaraní por ej. , como ya conoces.
Voy a leer los trabajos que me acercas.  En el caso de las islas  actuales del Paraná no me atrevo a generalizar respecto del funcionamiento: agua superficial/agua subterránea. ya que hay diferentes escenarios.
En el caso de Iberá, y su entorno (que es mi objeto de análisis) todo el paisaje está incluido en el paleoabanico fliuvial del Paraná. Los paisajes "terrestres" que rodean al humedal, corresponden a las barras de arena que dejó el Paraná y que sobresalen un par de metros sobre el humedal, pero que tienen una potencia de 40-70 m de arenas.  Abajo de este paquete de arenas estaría el primer acuífero verdadero, sobre el basalto 
El nivel de base de las lagunas del humedal está en los cinco metros respecto de la lámina de agua.  No se han completado los estudios hidrogelógicos aún (están trabajando  varios grupos (Luis Vives, la gente de la UNL de Sta. Fe, otros 2 grupos más). Seguramente la recarga del sistema tiene muchísimo que ver con un área de aporte mucho más amplia que la zona en la que estan los pinos alrededor... 
Pero nadie de ellos me dice lo que necesito saber: TENDRÁN LOS PINOS UN EFECTO ADVERSO SOBRE LA DINÁMICA ACTUAL DEL HUMEDAL?
Esto es un asunto clave, amigo!
Gracias por tu ayuda. Un abrazo bien fuerte.
JJ
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For slurry head losses or limiting velocities expressions developing process, it is important to have calibration information, but it is very hard to find works related to industrial (mineral ore) slurries, but very easy to find sand-water slurry data.
I would like if it is there any researcher looking for something similar?
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Dear Sirous,
sorry you fail to see the humor, the acronym was absolutely not intended to shock people.
kind regards
Francois Clemens
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end
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What about something similar to fixing the value of your scalar in the unconsidered region as suggested in ...
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(i) How does spatial and temporal distribution of radio-nuclide concentration get distributed as soon as it leaches out of the disposal facility, particularly in the near field, and that too, in the absence of thermodynamic equilibrium?
(ii) What is the rate at which the mobility of radio-nuclides takes place soon after its release from the disposal facilities?
(iii) What happens to mixing or spreading details of radioactive wastes within the subsurface system associated with different disposal practices connected with different depths/geology?
(iv) How fast the nuclear wastes gets diluted, especially within deep-seated unweathered hard rock?
(v) In case, if the nuclear waste (or radionuclides) leaches out of the repository, will the concentration of the soluble species such as Cesium and Technetium be diluted to natural background level, and if so, what is the associated rate at which the concentration of radionuclides gets diluted?
(vi) What happens to the concentration of insoluble species such as Plutonium?
(vii) What is the likelihood of leached radioactive wastes reaching all the way to the biosphere from geosphere?
(viii) Whether the concept of nuclear heat associated with the subsurface and deep geological disposal require the transport of thermal fronts with
reference to the transport of solutes?
(ix) How far colloids influence the radionuclide migration? and
(x) Whether NAPL behavior has a significant role to play with, in the vicinity of a Nuclear Waste Repository?
Reference:
ISH Journal of Hydraulic Engineering, 2015, Vol. 21, No. 2, 162–176
Suresh Kumar
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Heat from buried waste mobilizes groundwaters, initiating convective overturn that destroys site integrity.  I was with State of Nevada Yucca Mountain Project University of Nevada, Reno Nevada found burial ruinous.  .
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I have 4500 images at a single measurements, and each file contain 3970 numbers of u,v,x and y. So it is difficult on part of me to the averaging and to get a longitudinal velocity profile. So kindly help me
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Hello, it may be useful this web... http://ptvlab.blogspot.com.ar
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Does anyone know any CFD modeling software that can be used for hydraulic computation purpose?
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There are a lot of software which based on special issue you can use:
Flow 3D: provides a powerful tool for complex fluid modeling problems. FLOW-3D enables highly accurate simulations of free-surface flows using TruVOF, the original and true form of the Volume-of-Fluid technique.
Fluent: includes well-validated physical modeling capabilities to deliver fast, accurate results across the widest range of CFD and multi-physics applications
Delft 3D: 3D modeling suite to investigate hydrodynamics, sediment transport and morphology and water quality for fluvial, estuarine and coastal environments.
HECRAS: one-dimensional steady flow, one and two-dimensional unsteady flow calculations, sediment transport/mobile bed computations, and water temperature/water quality modeling.
Mike11: Rivers and reservoirs, Forecasting, Hydrology, Sediments, Water quality
OpeanFoam: has an extensive range of features to solve anything from complex fluid flows involving chemical reactions, turbulence and heat transfer, to acoustics, solid mechanics and electromagnetics.
Comsol: software solutions for multiphysics modeling.
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hello Everyone !!!!
i would like to measure velocity of flow in XYZ direction near the surface of pier ,yes we do have ADV and i can measure velocity atleast 7cm away from the surface of pier, so how can i measure the velocity within 7cm radius from the pier ? 
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Because of the configuration of the ADV of downlooking probe, the uppermost 7 cm of the flow could not be sampled. This distance should be decreased with the use of a sidelooking probe.
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Would appreciate research comprising sustainable and cost effective weir design solutions.
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Dear Michael,
Current research focuses on Piano Key Weir. Tested since 15 years and implemented on many dams in various countries since 10 years, the Piano Key Weir represents an improved labyrinth design, which appears very cost efficient, optimizing hydraulic efficiency as well as structural requirements and construction facility. Piano Key Weirs (PK Weirs) triple the spillways discharge.
With my best regards
Prof. Bachir ACHOUR
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Hi, when I analyze the small sphere fall in still water with acceleration, is there a suitable equation to illustrate its relaxation time  on the sphere velocity?  Thank you in advance!
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Dear Aimen Zeiny,
Thanks a lot for your kind reply.In these days, I am always looking for a suitable equation for the acceleration fall of a sphere in still water. So I looked around the reference by accident. I would understand the reference and your recommended equation in details.
Best regards,
Zegao
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I am doing an experiment in a hydraulic flume to study velocity field and flow structure in vicinity of a retaining wall. I am using PIV and currently looking for a way to shoot laser from top of the free surface (to study flow structure under the free surface) without putting plexi glass or any other material which may pressurize the flow. Any idea or suggestion? 
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Dear Nasser,
You can put the laser beneath the flume and make a perspex tower for the light sheet, or put it on the side (if you have a transparent wall) and use a mirror to shift the sheet by 90 degrees.
Regards,
Dubravka Pokrajac
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Hello Mr Shabbir,
If I have understood your question right and read your explanation it could be that you mixed up some things.
In my understanding its
Hydraulic cylinder :
p(hyd)= F/ A(cylinder)  with the area of your cylinderpiston
Surface Force Stamp:  
Sigma(surf.press)= F/ A(pressing area)  -> F = sigma * A(pressing area)
Thus:
p(hyd)= sigma(surf.press) * A(pressing area) / A(cylinder)
A(pressing area) / A(cylinder) = K (constant)
Thus:
p(hyd)= sigma(surf.press) * K
Now you can translate your p(hyd) from you gauge into a Surface pressure which exists at your stamp.
regards,
Kamil Wlotzka
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I want to calibrate the daily sediment data by using SWAT-CUP.
I don't found the exact format of daily observed data to edit into SWAT-CUP and so that the calibration process is not completed.
Kindly provide the exact FORMAT for "DAILY OBSERVED DATA TO BE USED IN SWAT-CUP.
Thanking you. 
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i would like to learn about the calculations formulas involve in this mechanism.
Any notes or formulas with explaination on the calculations of pressure loss, volumentric velocity, velocity, ect. will be very much helpful.
In the pdf of the given link, the hydraulic loss coefficient was not clear to me.
at the end results, i want to learn how to determine a right conical vortex regulator size when i have a wanted pressure loss, velocity ect.
If there´s a price range for the conical vortex regulator according to size..it will be very much helpful too.
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thx =)
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i want to solve this system of ODE, i.e, solving two equations simultaneously...
what method would you recommend me?
please explain your recommended method.
thanks 
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You have decorated your variables with a lot of indices which probably are important to you, but which are only distracting to outsiders. It would have been much more informative if you had indicated which quantities are time dependent, and which are just plain constants. As already said by Gustaf, this looks like the Hamilton equations.
For a Hamiltonian of the form
H = a p2 + b ln(q) + f(t) p + g(t) q, a and b constants
There is no way to integrate this equation analytically; the numerical method suggested by Gustaf seems reasonable. However, for a first attempt you may just as well use a standard library routine (which would be of higher order in the time-step than Störmer-Verlet). If f(t) and g(t) should happen to be constant, you can reduce the problem to one first order equation, making use of H being a constant of motion. But it is not obvious to me that this would be of much help, if any.
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I'm interested in measuring the temperature of the snow over its depth. The temperature should be measured in every 20-25 cm over the up to 2 m snow pack.
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Dear Tomasz,
I know very good book on the subject: S.D. Vinnikov & B.V. Proskuryakov "Hydrophysics", Leningrad,"Hydrometeoizdat", 1988  (unfortunately in Russian)
in which there described the structure of snow and its density. There are several  problems and solutions for multi layer matter, for example snow above ice.
Best wishes
Elena Dolgopolova
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Have Regime Equations in designing canals usefulness?
BUT Take into account that canals have routine maintenance program or growing of vegetation
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Regime equations such as proposed by Lacey, Blench and others are of course empirical in their development and one needs to be careful whenever they are applied  outside of the range of conditions for which they were derived, a detail that is all too often neglected in practice in this and other hydraulic applications.  Nevertheless, there are many such relations that have also been derived from observations in natural rivers, provided that an effective or channel forming discharge is estimated.  Since many of these relations are in a power law form, it is instructive to compare exponents in such relations and they tend to be fairly similar for most of the equations although sometimes it is hard to make a direct comparison because of the choice of variables in the generated equation.  This would lead one to conclude that there is some general value in such relations provide that the discharge is fairlyty constant or that the channel forming discharge is estimated.
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The wastewater from a restaurant (about 40 m3/day) enter to an equalization tank (dimension W*L*H= 1*3*4 m) before an anaerobic system.
What is your idea and experience about the  installation of a non clog pump in equalization tank for discharge waste water to an ABR? 
Is it possible to have a pump with differential discharge or regulation ability, for example 0.5 untill 3 m3 per hour. Off course we can install a fixed discharge pump, with a bypass flow to the system for regulating the outlet flow.
What is your idea for the type of pump and required power?
If you have any experience or design for the same condition, please write your idea for this design.
thanks for your reply
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Dear Zabihollah,
We use non-clogging centrifugal pumps with variable speed/frequency drive (VSD/VFD) with electromagnetic (EM) flowmeter in the discharge for automatic flow control adjustable over a wide range. In our projects we adjust the outgoing flow rate automatically to the wastewater level in the EQ tank as to get full equalization by master-slave PID control.
By the way, Prem's formula calculates only the theoretical hydraulic power but not the real pump power (mechanical or electrical  power uptake). For small pumps such as in your application the overall efficiency hydraulic to electrical power could be less than 20% resulting in more than 5 times higher electrical power consumption as compared to the theoretical hydraulic power.
Finally, the "h" in Prem's formula shall be the Total Dynamic Head TDH = static head + head losses in piping and valves.
Regards,
Bruno
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Is manning equations the best method to determine the discharges in open channels?
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Dear Mahmoud,
Formulas such as Manning or Chezy are widely used. But the major problem is the evaluation of the Manning coefficient or that of Chezy. Usually, a constant value is assigned to Manning coefficient to solve the problem of computing the discharge or the assessment of normal depth. In recent years, studies have shown that these coefficients are not constant but depend primarily on the relative roughness (and therefore the absolute roughness characterizing the state of the inner wall of the channel), the aspect ratio of the water area and especially on the Reynolds number demonstrates the effect of kinematic viscosity. From these considerations, it was able to establish a general relationship of the discharge in a channel (or pipe) that takes into account all parameters influencing the flow. It is very well explained and demonstrates in the article that I join you (in particular relations 1.19 and 1.20)
With my best regards
Prof. Bachir ACHOUR
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Can anyone help direct me to papers or books about River island formations?
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Hi,
Generally, the river islands are formed in the middle and lower reaches of the river. The formation of the islands also depend on the type of river, sediment type, stream capacity/ estream energy level. So according to this, you should find the literature. 
You may regfer Knighton's articles and book.
Good luck
Supriti
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is it possible to calibrate the swat model to estimate sediment yield without observed data?
Swat model calibation for unguauged watershed?
Pls guide me..
Thanking you
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@Arun,
I do support the GIL`s idea and also his suggestion.
Please have a look on the following discussion regarding your query.
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if any one have papers in yhdraulic field past than 1950 ?
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Dear Ahmed,
Please tell me which paper do you need.
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I am performing simulation analysis for an agricultural vehicle HST control system. I need to obtain temperature variated flow rates for its pumps and motor. It is known that volumetric efficiency decreases with temperature and hydro mechanical efficiency follows the opposite trend. Can I obtain a mathematical basis for this for general test conditions , so that I can quantity and build simulation models based on this relationship.
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Are Ameya!
Navin Varshachya Shubhechcha!
What I suggest is first make a small-scale working model of the setup and monitor the temperature and pressure parameters as your primary data. Based on the trend analysis, you can obtain your own mathematical model to evaluate. Sometimes to obtain "STRAIGHT-FORWARD ENGINEERING SOLUTIONS"  we need to adopt or apply "REVERSE METHODOLOGIES".
Best Luck!
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dear all :
am looking for the hydraulic details for  culverts or extra details for the purpose ( using flushing culverts ) in the body of the breakwaters in harbor connected with the basin for improving water circulation at the basin.
I would appreciate any advises, helps, recommendations.
thank you 
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thank you dear I got it 
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I have broblem with understandig what exactly is the parameter R ?and can we show it in the control volume?
if you help me with this i will be very thankfull.
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Dear Farnaz Binazadeh,
Please explain more about your issue. Which equation do you mean?
May you share the book/chapter/article that you read about jet scour in equilibrium phase?
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Is it specific to the composition of the anolyte and desired outcome? Or is there a general value?
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 Without an understanding of the application under consideration, wish to add that the permeability of the surrounding medium would be a factor which is expected to have an impact on the hydraulic retention time.
Would be delighted to know more about the study problem.
Best regards,
Sarosh
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It is assumed that to be a two stage system, the HRT should be greater in the acidogenic reactor because the hydrolysis step is which required most time.
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HRT should be designed considering the growth kinetics of the microbial consortia. Fermentative consortia have faster growth kinetics compared to methanogens in the second stage, thus the HRT in the methanogenic stage i.e. second stage is higher than the first stage. 
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The conventional rational method or its derivate is still very used for dimensioning and calculating separate urban storm water networks. What are the main reasons for the use of the classic formulation to be normally limited to small drainage basins? The conventional method overestimates or underestimates water flow rates? Is it safe or insecure? The water flow rates for the dimensioning and the calculation of the networks should be increased or decreased?
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Thanks Dear Ljubomir and Dear Mohan for the pertinent links selected. According to one of the links that Ljubomir selected “Estimating Storm Water Runoff” from 2012, by John Poullain (PE):
“Limitations of the Formula: The major limitation is that the Rational Formula only produces one point on the runoff hydrograph--the peak discharge rate. When basins become complex, and where sub-basins combine, the Rational Formula will tend to overestimate the actual flow. The over estimation will result in the oversizing of stormwater management systems.”
In fact I obtained results in the opposite direction. The classic Rational Method is a kinematic method (i.e., it assumes that the maximum flow occurs when whole upstream drainage basin is contributing for the formation of the flow in the sewer section, for a time of precipitation, Tp, equal to the time of the concentration of the basin in that section, Tc), assuming implicitly a symmetric triangular hydrograph of base 2Tc. The intensity of precipitation decreases, in the curves of Intensity-Duration-Frequency (IDF curves), for a given Period of Return, TR, when the time of precipitation increases. Higher Intensities of precipitation during periods shorter than Tc can produce higher peak flows, even if not all area of the drainage basin contributes for the formation of the peak flow. The decrease of the intensity of precipitation with the time of transportation in the pipe sewers in the rational method may produce a larger decrease in the peak flow than the effects of propagation, attenuation and storage in the pipe sewers, as I demonstrated with a very simple example in the conference article from 1996 in attachment of my first answer. I confirmed those results also for tree-like networks (arborescent networks) in a more elaborated example that I developed on that time.
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hi
how can I Calculate head loss of a drop manhole?
is any design chart or solved example for it?!
Thank
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Ok, so you basically need the loss coefficients. You can use the two tables on page 10.
First you have to check what type of manhole you are trying to calculate and choose one of the two tables accordingly. Now the loss coefficients depend on the flow conditions (partially full, full, impounded) and how much the flow will change direction inside the manholes.
The first and second column refer to the same, that is the flow conditions and it translates like this:
Ablusssituation = Flow Conditions
- Teilfühlung = partially full
- Scheitelfühlung = full flow
-Einstau = impounded flow
Now I guess from your drawing that you are not expecting direction changes in your flow within the manholes, so you would get your coefficients from the third column on these tables. In case you wonder Umlenkung means something like redirection (direction change). Hope it helps.
Finally and just as a note there is the last row of both tables, this is something special. If you place a perforated plate inside the manholes where the "roof" of the pipes would be, you can reduce the losses. I know about two studies regarding this issue, one was carried out at my laboratory. You can get an idea of its effect by looking at the "turbulence intensity"  with and without perforated plate, for which I have attached two images.
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I am looking for Moritz Weber's theory and experiment to determine the Weber number.
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Hello
I think this book can be helpful. It contains many modelling conditions. You can find information about Weber number in these conditions
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How much artificial aeration methods, such as constructing cascades or weirs, using mechanical aerators, floated plants, or pumping out and discharging again the water, can increase the rearation rate (Ka) of rivers? Is there any practical case study pointing to this fact?
I know that this depends on various parameters, and I dont need the aeration potential of these methods. I am really looking forward to any literature, case study or report that directly shows Ka is changed from X to Y in rivers.
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Hi!
What kind of rivers are interesting for you? You mean to mountain or lowland rivers?
The aerations problems is only in rivers, which have very high level of organic pollution. You have this problem or any other problems.
Your problems are local or they concerned the river on the whole?
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I am currently designing the hydraulic system of a refuse compactor vehicle. I'm having a problem in choosing the correct method to choose the best working pressure and temperature in order to produce high efficiency.
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Thanks for the answers from all of you, Much appreciated.
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Can any anyone suggest any method or model to optimize energy production in Hydropower plant?
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Dear Alban,
As in any optimization problem, you have to start by defining your objective function and the constraints under which your problem is intended to operate.
My suggestion is to use a Life-Cycle-Cost Analysis (LCCA) in which you consider not only the energy generation, but also, as my colleague mentioned before, the demand and the possibility to access to incentives to the production of electricity by hydropower means (FIT, for example). Consider, also, what is the alternative you are competing against. For example, if it´s a rural community, probably you are competing against a Diesel plant.
In the problem, you have to consider the Flow Duration Curve, the head, the existence or not of dam, connection to grid, etc. In general, you´ll have to assess initial costs and operating and maintenance costs and compare in a LCCA to costs of using conventional sources. Then, once you have the model to perform NPV, IRR, B-C ratio, etc., you can focus on running the optimization algorithm on input variables to find the optimal combination to obtain the largest benefit from your investment (you may focus for example on NPV if this is yor Objective Function).
Besides the recommendations given by previous colleagues, I suggest to pay attention to software like RETScreen (free at: www.retscreen.net) or HOMER (Legacy version is free).
If you use RETScreen, you´ll need to run the optimization algorithm on the MS-Excel platform it´s embedded within or extract the data to another tool. RETScreen calculates the advantage or disadvantage of a proposed mini-hydro system vs. the conventional supply unit. It allows you also to perform sensitivity and risk analyses on the selected option. 
To have an idea on how RETScreen can help you in setting up mini-hydro projects (as the base for the optimization analysis), you can take a look at these two case studies prepared by my former master students:
I hope it helps to develop your project.
Best regards,
Luis
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