Viscosity - Science topic
Viscosity is the resistance that a gaseous or liquid system offers to flow when it is subjected to shear stress. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Questions related to Viscosity
Mostly, when I measure the viscosity of liquid material at constant shear rate for 10 min , the value does not change with time . But, during the measurement of viscosity of nanocomposite fluid at constant shear rate, I noticed the viscosity changes between two values in the regular pattern.
Hi, I want to sterilize the chitosan solution (for microbiological purposes). I don't want to autoclave the solution as it might affect the heat-sensitive additives in the solution. Also, I am not sure if I can use membrane filters as the viscosity of the solution is very high. Are there any suggestions?
This is an anectdotal experience- i mixed two brands of liquid handwash soap without adding any water, and the mixture surprisingly appears less viscous (I have not measured with any device, but can tell from ease of flow) in winter months compared to standard handwash soaps I experienced in summer. can you tell why?
The handwashes are not alcohol or glycerine based- these are soap based. I know sodium stearate, palmeate, oleate etc. are main components of body washing solid soaps. Using potassium instead of sodium makes the soaps softer. and the liquid soaps are sodium laureth or pareth sulfate (or sulfonate?) based. This is not like deteregent where cationic and anoic detergent mixed together produces a buch of much-less water soluble entangled polymers. Even If I assume (polymeric) ionic liquid formation scope, even then viscosity reducing with temperature does not make any sense. Or does it? I know thermoplastics show higher elastic modulus at higher temperature sometimes due to entropic effect. Is something like that happening here? can you tell me whether there ane widely circulated liquid-soap-based handwashes that are not laureth or pareth based? Or what can be the role played by additives into the handwash?
plz recomend methods
i have a problem about Mixing in pipe(polymerization).
because of polymerization speed(too fast), static mixer used to be blocked with gel(polymer gel).
so i need pre-mixing front of static mixer.
i thought about method
mixing plate (make turbulant flow) -> raw material's viscosity is high (X)
jet mixer -> can make a gel (fast polymerization) -> can be block the injector hole
so to solve a problem plz recomend any method which have a small possibility !
How can I reduce the viscosity of saliva samples for the proteomics project and homogenize the samples viscosely?
It should be noted that I do not want proteins to be removed in this way
How should I set the viscous resistance coefficient and hydrodynamic resistance coefficient to describe the free exchange of gases between two gas chambers by bulk viscosity? I have been searching for a long time, but I can't find them.
ps:I know how to establish fluid exchange, but how should the two parameters viscous resistance coefficient and hydrodynamic resistance coefficient be calculated (e.g. air)
I am doing a CFD simulation for waste heat boiler and simulation boiling in steam drum.
I used ANSYS Fluent to perform the simulation. However during the calculation section. I received this error
"reversed flow in 274 faces on pressure-outlet 18.
Stabilizing mp-x-momentum to enhance linear solver robustness.
Stabilizing k to enhance linear solver robustness.
Divergence detected in AMG solver: k temperature limited to 1.000000e+00 in 8519 cells on zone 2 in domain 3
turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 18252 cells
Divergence detected in AMG solver: k
Error at host: floating point exception
Error at Node 0: floating point exception
Error at Node 1: floating point exception
Error: floating point exception
Error Object: #f"
May I know what are the possible cause of this error?
Any advice? Thank you
Is there any correlation between MFI and viscosity, measured i.e. with Brookfield viscosimeter? In particular for linear polymers.
I have found EPOON 1004F epoxy resin with good viscosity, but I am not sure how to use it. Could you please tell me how to use EPOON 1004F epoxy resin before? Thank you very much.
Address of attached materials:
I have scaled down my geometry 1:1000 ratio. During simulation, if I input the velocity parameter same as the actual case, will it be considered as correct procedure or not?
This developed turbulent flow codes is a finite element computer model, written in FORTRAN which was developed to solve the Reynolds equations of motion and continuity for steady and fully developed mean turbulent flow. The Finite Element mathematical treatment of this matter is reported in the following Ph.D. reference at CSU, Fort Collins, Co, the USA (please the link to this dissertation is https://mountainscholar.org/handle/10217/235417). Later on this code was extended to three dimensional and unsteady flows. The turbulent stresses appearing in the Reynolds equations are modeled in terms of mean velocity nonlinear gradients and turbulent viscosity. The non-linear algebraic stress model used in closed channels is totally different from the one used in open channels with new algebraic open surface proximity functions. A two equation turbulence model consisting of the turbulent kinetic energy (K), and its rate of dissipation (ε) evaluates the turbulent viscosity that appears in the algebraic stress models.
For wall bounded flows especially at corners (such as at an airplane's body to wing), my code succeeded in an excellent manner in simulating the main velocity, secondary velocities and turbulence structure (turbulent viscosity, K, and ε). In addition, distributions of the non-gravitational pressure and turbulent stresses are well predicted too. You may contact me for samples of the results of simulating turbulent flow in a square duct. Along the corner bisector the maximum secondary velocity divided by the average shear velocity is calculated as 0.31 which is in agreement with experimental data of Brundrett & Baines (1964) of about 0.32. For the wall bisector a value of 0.21 is predicted versus a measured value of 0.20 by Gessner and Emery 1980. Bulging of the velocity contours toward the corner is well predicted which is important in reducing separation due to adverse longitudinal pressure gradients. No up-winding or (over/under) relaxation are used. Non-linear Newton–Raphson that has quadratic convergence is used for dealing with the system of nonlinear equations. The boundary shear stress is calculated and is shown to be affected by the secondary velocities.
- For open channel flows: a very distinct feature in my nonlinear k-ε model is the use of an-isotropic turbulent viscosity in which the turbulent viscosity in the vertical direction differs from that in the lateral direction, a feature not existing in any existing CFD code to my knowledge. The model succeeded in predicting the depression in the main velocity maximum to be at 0.6 from the bed in a channel with aspect ratio of 1:2. The secondary velocity structure is also well predicted . Another important feature is prediction of the cellular secondary cells due to periodic roughness changes along the bed or walls. This helps in investigation of flow over ribbed surfaces.
Now How much does the source code for this turbulent flow CFD code worth in US $?
I appreciate honest answers and offers.
For more details I can be reached at my email:
We have been using PEG-8000 (10%) and NaCl (0.5 M) precipitation for concentrating phage samples before ultracentrifugation and for some of them, we got a really viscous solution after PEG precipitation. Adding DNase I has not helped. Why this high viscosity and what to do to get rid of it? Using samples as they are for ultracentrifugation gives no visible virus bands.
I am having trouble with C2C12 cells detaching from the well plates after adding conditioned media. Areas on the left and bottom sides of the wells lack cells after switching to the conditioned media. I assume it is due to the media's higher viscosity than PBS as they only dislodged during the media change and not the PBS wash.
Is there any way to prevent the cells from dislodging when I add the media? Any help would be greatly appreciated!
1. cells were seeded 24 hours before the media change
2. media aliquoted with single-channel micropipette against the wall.
Why does the non ionic surfactant, polysorbate 80, decrease the viscosity in a constant PVP ethanol polymer solution, yet at the same time, increase the diameter of its electrospun nanofibres?
Can't find anything in literature, nor in any organic pathways!
I needed published articles or any applying reference with experimental data on how temperature affects the settling velocity of particles. How the temperature change also affect the kinematic viscosity of fluid.
I hope you are doing well!
I am currently doing research in the field of additive manufacturing with technical ceramics, and I have two separate questions specifically regarding silicon dioxide (SiO2).
1. In 3D printing with SiO2, I use a slurry mixture which is composed of SiO2 powder, deionized water, DARVAN C-N (for dispersant) and CELLOSIZE Texture F4M (for binder). The CELLOSIZE Texture F4M is cold-water dispersible hydroxypropyl methylcellulose which is primarily used to control viscosity within the slurry. My main issue is when I add the binder into my SiO2 slurry and mix it, the slurry almost becomes a non-Newtonian liquid within 20 seconds, in that sudden impact hardens the overall slurry and after the impact it immediately goes back to a viscous state. Could you please point me to any research regarding this issue? Additionally, I've tried the same binder on alumina and silicon carbide (other technical ceramics) and haven't faced this issue. I've also experimented with modifying different speeds of mixing, gradual increments of adding the binder, and mixing in a vacuum environment; however, none of these helped. Could it be that methylcellulose reacts chemically with SiO2, and a different binder should be used?
2. For sintering ceramics, I've read that ~80% of the melting temperature is a good baseline for experimentation. My goal is to increase part density and flexural strength. Could you please point me to any research regarding selecting a sintering schedule (time and temperature) for silica specifically? I've read through literature suggesting ~1300C for around 8 hours with a heating rate of 5C/min; however, I'm curious if a lower temperature such as 900C for a longer sintering time or a higher temperature of 1500C for a shorter sintering time would vary the final part density and flexural strength significantly. I'm currently only experimenting with single-stage sintering.
I appreciate all your help and insight.
Thanks & Regards,
I am seeking to increase the viscosity of my mammalian cell culture medium while minimizing non-viscosity related effects on my cells.
Do you have any specific protocol and compounds to suggest?
I have ordered high MW dextran sulfate (Sigma D8906), but I am worried by the fact that the only recommended use is nucleic acids hybridization.
Is there any other type of dextran that would be better suited for cell culture?
Thank you for your help.
I am trying to use powder NaCMC (High Viscosity 1100-1900 CPS) as a dispersion agent for dispersing chopped carbon fiber in the concrete mix, but the problem lies in the solubility of NaCMC in water. After adding certain amount of NaCMC in water it forms a lump and floats in beaker. So my question is does the viscosity of chemical affect the solubility in water. If not then what are the ways to increase solubility of NaCMC in water.
Hi, I'm new to rheology and viscosity study. I have emulsion samples containing clay, polymer, and emulsifier. The difference between the samples is just clay concentrations and oil constituents which give them different viscosity from low to medium viscosity (0.2 - 31 Pa.s). The current rheometer I have in the lab is Rheosys Merlin II (controlled shear rate rheometer). The goal of the rheometry analysis is to assess:
1. Apparent viscosity
2. Shear thinning (viscosity slope)
3. Yield stress
For the preset, I can only use shear rate. I have the range of shear stress, viscosity, time, and torque results generated from shear rate of 1s-1 to 1000 s-1 (10 data points per decade; three decades; 10 seconds measuring duration per data). I found out that some medium viscosity samples experienced solvent evaporation, so maybe I will try 5 seconds instead of 10 seconds.
So, my question is:
I found that several references told me to not use curve fitting models for yield stress determination since those methods are only used for simple QC tests and not for modern RnD work. Can you recommend to me which yield stress method with the preset controlled shear rate that I can use instead of curve fitting models? I plan to use a single fitting line because it provides yield point of "reversible deformed" behavior that may benefit the next analysis: thixotropy. But the method can only be used for the preset controlled shear stress. Anyone can help me?
I synthesized high viscosity phenolic formaldehyde resin with viscosity about 5000-6000 cPs with pH about 8-8.5 (I used alkaline catalyst e.g NaOH). Viscosity of resin decreased drastically (more than 70%) after I just added 10% of water. For coating of cloth backing material application needs resin with lower solubility in water (viscosity will not decrease drastically after add 10-20% of water).
I tried to investigate the rheological properties of okra mucilage under shear and oscillation condition. When I make a comparison between shear viscosity and complex viscosity, the result is shown as attached (The complex viscosity increases suddenly when frequency is high enough). Can someone give me a reason for this phenomenon, please?
Thank you very much.
I've heard that Einstein come up with a model for how many spheres could we have in liquid without influence to viscosity.
Is there any paper that deals with this?
All, It's known of curse that viscosity depends on pressure. Often this dependence is weak and sometimes it is significant. It is an odd and unmotivated question but, nevertheless, I am wondering if our parameterizations of turbulent viscosities should also include some measure of local pressure fluctuations? (This may be a question resolved long ago by people doing compressible turbulence.) I'm hoping to learn from people's answers and ideas. Thanks! Bill
I would prefer liquids in the 50-100 cps range that will not change viscosity as much over a temperature range of 22-50 degrees celcius.
Can chemicals ( demulsifier or fast dropper) be used to separate water from Heavy crude oil to prepare for the following tests (viscosity, asphaltene deposition, SARA test and flash point)? Is this ASTM compliant?
I am trying to characterize the viscosity of newly developed cell culture media formulation. WE have AR2000Ex Rheometer. I am wondering what could be the values for the parameters to setup for the characterization, especially (a) Range of shear rate (1/s); (b) Gap between the plates; (c) Normal force; (d) diameter of parallel plates; (e) angular velocity (w); and any additional parameters I should consider? Really appreciate any inputs which can help us to get started.
I am doing research on sand erosion experiment. What are the chemicals or additives that can be added to water to simulate the fluid properties of crude oil ( e.g viscosity and density of crude oil) ? Other than glycerin water mixture, what else i can add to water to simulate the viscosity and density of crude oil ?
I was looking for silicone oil based shear thinning liquids. I could't find one yet,
so i was trying to address this issue by dissolving polymers in silicone oils. I tried PEO and Xanthan gum but there was no homogeneous mixture. I want the dynamic viscosity be less than 1000mPa.s .
Appreciate your recommendations
Being aware of the hazardous nature of both phenol and 1,1,2,2 tetrachloroethane, I don't want to take any risk of not being sure about the procedure. I know this solvent mixture is commercially available, but in my case I have phenol (crystals) and 1,1,2,2 tetracholoroethane (98% solution) separately; I need this solution for the ASTM D4603 method to determine the inherent viscosity of PET.
If anybody here has made the Phenol/1,1,2,2 tetracholoroethane (60:40 w/w) solution by himself, please share your practical experience with me.
Thank you in advance for any help.
I am trying to simulate miscible liquids in fluent. I am trying to reproduce the results of a paper, but I am not getting the same mass fraction plots as in the paper. I am using species transport model with laminar flow model. I have set the viscosity and molecular diffusion coefficient values as given in the paper. I have tried 4 different sets of mesh based on cell count and refinement. I cannot seem to know what may be the problem
I am looking to melt extrude PLA and a microcellulosic filler in a single screw extruder. The concern is insufficient back pressure due to low polymer viscosity before the compression zone. I want the polymer to be softened up instead of losing viscosity. This is the context in which I want to ask if Tg and softening temperatures are the same or different. If so, can a test method for gauging the softening point (temperature) of semicrystalline polymers and composites be shared?
Ansys normally takes the Bulk Viscosity Coefficient (mu_b) as zero in all simulations. However, there are some cases of supersonic flows where mu_b is non-negligible. For such a case, how can we modify the momentum equations in Ansys to add the contribution of bulk viscosity ?
I recently using the Bio-Rad droplet PCR kit for a qPCR application, However, I realized that the generated droplets' viscosity increased a lot after thermal cycling (40X).
Then, I replaced the Bio-Rad oil system using Novec 7500 +5% Picosurf, the viscosity did not increase.
So if use entire kit from Bio-rad the droplet viscosity increased after Thermal cycling
If use Novec 7500 +Bio-rad reagent supermix for the aqueous phase, no increase in viscosity.
Does anyone know what makes the viscosity increased?
I have difficulty to merge these high viscosity droplets with another droplets library for downstream assay
I used Brookfield DVNEXT RHEOMETER and found the values of viscosity without the values of density. Now I am trying to find the viscosity average molecular weight of the polymer.
Do you have any reference/paper/document including the data/information or correlation(s) for the viscosity of lactose solution with various concentration at different temperatures?
Although capillary or falling ball viscometers are used but if we wish to get it via rheometer.
Any experts who can give light on this topic especially with reference to PVC solutions.
We fabricated the composite of PVA and nano-carbon-particles. The results of zeta sizer show that the size of PVA chains is increased and nano-carbon serves as a crosslinker. But in the case of rheometer's results, the viscosity of the above sample is decreased, which shows that nano-carbon serves as surfactant. The mechanical properties of composite structure are enhanced and XRD shows that the crystalline regions are less in the composite structure. What could be the possible reason of decrease in viscosity in your opinion ?
Here i have attached some XRD, zeta sizer and rheometer results..
I want to design an experiment for measuring the melting, hardening rates of different types of plastics. The equipment that are current available includes; a closed furnace with control valve, thermocouple, infrared thermometer, crucible and stopwatch.
Does anyone have any experience / advice on stabilizing solutions with heavy fumed silica loading (~60%)?
I am seeing odd viscosity behavior in my system where stored solutions are showing a kind of viscosity gradient with the bottom being less viscous than the top. Are agglomerates of fumed silica forming and rising to the surface? The solution doesn't have a noticeable visual indication of any sort of separation.
Any advice you can give into this phenomenon and how to stabilize it would be greatly appreciated.
What apparatus can be used to measure shear strain rate and viscosity for a non-newtonian fluid? Could it be done using the conventional spindle Brookfield viscometer?
There are different semi-empirical correlations for estimating the binary diffusion coefficient of liquids. For example, correlations involving the formation of complexes covering the low viscosity solvent, correlations involving high viscosity solvents, correlations incorporating the solute-solvent interaction, and correlations containing the effect of solvent association (Wilke and Chang equation).
The Wilke and Chang correlation is one of the most widely used to estimate binary diffusivity. However, in this equation, there is a parameter called solvent association (φ), and its value depends on the type of solvent. Does anyone know how to determine this solvent association parameter (φ)?
I add the equation of Wilke and chang in the annex.
I need to make a polyvinyl acetate homopolymer in ethanol. But I require high viscosity (60000 cPs). I solved the problem using 30% ethanol and 70% ethyl acetate but the customer don't like the product's smell.
i need to get polystyrene nanofibers. Kindly help me with the viscosity parameter
I am researching making droplets using Microfluidics technology.
To create smaller, immiscible droplets, I want to use a very high viscosity (biocompatible oil would be better!) oil.
I tried increasing the content of surfactant, but there was a limit. So far, I have tried Hexadecane ( 2.11cSt ), Light mineral oil ( 17cSt ), Heavy mineral oil ( 65-75cSt ), and Soy bean oil ( 50cSt ).
Any good suggestions would be appreciated.
Im having trouble understanding why I am seeing increases in viscosity at low frequency and high temperature for some neat polymers. Ive attached an example with neat LDPE. Temperatures 110C - 170C behave like you would expect for a polymer but a 190C and 210C, the visosity starts to increase as the frequency reduces.
We've seen this in some composites, and Ive always assumed it has to do with some rheological percolation. But here you can see we have a neat polymer with no filler material, which shouldnt have any percolation effects.
I am trying to raise the melt viscosity of a PHA polymer however as it is microbially produced the MW is already very high and difficult to control, and the addition of crosslinking agents will compromise the biodegradation credential.
I need the change of the modulus of elasticity, the yield stress, and viscosity parameter with a change of temperatures from 25 degrees Celsius to 400 degrees Celsius... Thanks
I am doing a numerical study for a liquid crystal-colloid using Lattice Boltzmann method as the numerical tool. I am using a MRT-collision scheme in my model which allows me to choose the viscosity independently unlike the BGK operator where the viscosity depends on the relaxation time. But, when I convert the unit of physical parameters to LB units, the viscosity which I get is quite high (O~3) and is unacceptable. Am I allowed to choose the viscosity independently and not calculate it according to the lattice resolution?
When i try to measure the viscosity of my sample via rotational Viscometer, the spindle continues to rotate without giving the readout. I have waited for as long as 30 minutes but to no avail. Can anyone please guide me what's the reason behind this? I would highly appreciate..
I have been trying to prepare Co doped TiO2 nanoparticles through sol gel method. I have a issue where my gel usually forms after 24 hrs but it is dried and its not viscous anymore. Can anyone help me with suggestions on how to retain the viscosity of the gel
I want to manufature a chip for drop-seq. From previous studies 80-100 um depth has been used. The dripping crossing width is 94um. The drop size is required to be both 100 and 125. The inlet has some viscosity coming from cell lysate (CA-630) and Iodixanol (for cell suspension). Which depth is better and can easily realise both drop size?
I am interested in solving the dimensionless equations for a bubble motion in COMSOL Multiphysics. But do not how to enter the dimensionless equations for density, viscosity, Reynolds number, Weber number, and Froud number as given in the attached papers. Can anyone please help in this problem. I shall be very thankful.
In relation to the coupling of fluid flow (gasoline) with magnetic field (permanent magnet) in experimental articles it is mentioned that in the presence of magnetic field, fuel properties such as density, surface tension and viscosity will change. I simulated this problem numerically recruiting the finite element method but I don't see these changes. I appreciate your help in advance.
I am currently working on cosmetic formulations.
I transferred the samples of emulsion into 50 ml bottles.
They were then held for a week at either room temperature (23 ±1 °C) or -15 ±1 °C before being heated to 23±1 °C.
However, when I measured the viscosity of samples, it appears that the cold sample is more viscous after thawing.
Does anyone have any ideas on the cause of the increase?
For my research work I need the viscosity of quartzofeldspathic fluid in different metamorphic facies (specially, amphibolite). Is there any research work on this? Please help
I want to measure the zeta potential of spherical particles (d=30µm) with different surface modification. Unfortunately, the particles precipitate during measurement. Can I increase the viscosity of the fluid, e.g. by adding glycerin, to slow down the precipitation and enable reliable measurements? What other work-arounds are possible?
Note: I am not aiming for absolute values of zeta potential but rather would like to compare differently modified particles with each other and obtain a relative statement.
I got my viscosity study data which includes shear stress, shear rate, viscosity, and torque and now I want to find out how to calculate shear train, storage modulus, and loss modulus from these data?
I'm currently looking at the rheological properties of the polymer Xanthan Gum. focusing on its dynamic viscosity to be more specific. I'm assessing the effects of pH (ranging from 3.6 to 5.6, 0.4 increment, total of 6 pH's) on the dynamic viscosity of xanthan gum solution (dissolving xanthan gum powder into acetic buffer with equal ionic strength, concentration is kept at 0.04%).
Firstly, my viscosity data collected shows that, as pH increases from 3.6 to 4.0 then 4.4, the viscosity increases; but as I bring up the pH from 4.4 to 4.8, 4.8 to 5.2, then lastly 5.2 to 5.6, the increasing viscosity trend plateaus and the increase in viscosity is less significant compared to the 3.6-4.4 jump. At this range, does pH has an effect on the viscosity of xanthan gum based on its molecular configuration? Though some sources states that xanthan gum's viscosity remains stable and unchanged within the range of pH 3-12 at a high concentration like 1% not 0.04%, yet some suggest pH still plays an effect, though I'm not sure how on the chemical and molecular aspect.
A possible conjecture I can think of is the xanthan gum's order-disorder and helix-coil transition is affected by protonation. In figure 2, it demonstrates how electrolytes affect the structure of the polymer; in figure 3, it shows how at a state of a helical rod and no longer a random coil, it is capable to hydrogen bonds among each other. Hence, I'm wondering of pH plays an effect on it's structural transition, such that the increased intermolecular forces at the form of a helical rod would make it more viscous in solution.
Here are the resources I have used so far:
Brunchi, CE., Bercea, M., Morariu, S. et al. Some properties of xanthan gum in aqueous solutions: effect of temperature and pH. J Polym Res 23, 123 (2016). https://doi.org/10.1007/s10965-016-1015-4
During our rheological measurements, we have often solved one problem. We measure viscosity on an extrusion machine equipped with a rheological head. We need the value of density of rubber (ex. natural rubber) for the calculation of viscosity. The measurement is at an elevated temperature (ex. 110 °C).
When we measure the viscosity of plastic, it is simple, because we can measure the density on a melt flow index machine (MFI). Natural rubber is almost unmeasurable on MFI. So we tried the pycnometer, but there we can measure only to the app. 90 °C. We measure the density at four lower temperatures and we use some curve to get the density at elevated temperature. I think it is not the best technique, but we haven´t found better.
Thank you for some advice.
I am preparing a 5% GelMA hydrogel in PBS using APS and TEMED at 20mM concentration. Even after long exposure to UV, there doesn't seem to be any change in the precursor solution. Not even any viscosity changes. Any idea why this might be so? What might I be doing wrong?
I bought a XL7 viscometer to use on-line the production of adhesive and speed-up the process.
Nowadays, I use a Brookfield viscometer in lab. So I have to stop the production to take a sample to the lab and make the viscosity measurement.
I tried to make some measures with the XL7 in off-line, using it immersed in a sample like the Brookfield.
But the viscosty value are really different between the Brokfield and the XL7.
What can I do to find a conversion factor between the two viscometers for all my different types of adhesives?
what is the difference between the Kinematic Viscosity and dynamic viscosity， what is the applicable condition？