Ocean Waves - Science topic

That is whole new paradigm, Tony!! Quite interesting to see like the two types of oscillations with electromagnetic waves that I am developing alongside Emory Taylor with upcoming paper publications on extending Maxwellian electromagnetism and the photon constant of c of light.

Yet another aspect that I am developing alongside my coauthors will be the concept of the weak gravity versus strong gravity, which would explain all the vagaries that four fundamental forces act on - the strong nuclear, the weak nuclear, gravitational, and electromagnetic types. Finally, they can all be unified together under this umbrella eventually!!

Thank you with your innovative paradigm!!

Sincerely,

Rajan Iyer

ENGINEERINGINC INTERNATIONAL OPERATIONAL TEKNET EARTH GLOBAL

I suggest choosing Flowvision.

Create a calculation area. Water below, air above. Enter conditions at the boundaries. In the parallelepiped of air, it is possible to create wind (tangential stresses) and periodic changes in air pressure. Wave theory suggests two mechanisms - shear stresses and pressure changes. In the hydrodynamic model, only periodic changes in pressure above the water surface work. Shear stresses (wind) can be added to the calculation after the waves have formed. Consult the Flowvision website.

In the water waves are more mechanical in form and have a slower propagation velocity than air. In the first 500 feet the phase velocity is non-linear. I would recommend COMSOL acoustic simulation toolbox.

COMSOL is indeed great tool but i recommend CFD

Probably not and if you get something it would look neither quite good nor complete. Irrotationality condition is either implicitly (when derivation is done in terms of velocity potential) or explicitly (when the horizontal and vertical velocities are connected) is used in deriving Boussinesq-like equations--more generally depth-integrated wave equations. The use of irrotationality condition is in a sense obligatory to complete the system. I am attaching a paper of mine which shows these steps explicitly. See equations 15 to 23 but especially notice eqn. 18. I suppose there is no need to say KdV is a form of Boussinesq.

On the other hand, there is always Gerstner's rotational waves -exact solution- (see Lamb's Hyrodynamics, p. 421) but they really do not have a good reputation :) from the physical point of view.

Dear Satyam Chauhan ,

Welcome!

Sure you found a solution but I have a proposal that may help solve such problems.

At first one has to draw the wave profiles as w(x,t)

There are two waves, time waves at certain position.

And there is also position waves.

At first you can analyze these waveforms using Fourier transform such as fft.

After which you may decide on the low pass filter characteristics by setting the cut off frequency and the stop frequency and the stop band attenuation.

Then give such specifications one can design the low pass filter. either analog of digital.

Best wishes

For JONSWAP, please check:

https://www.researchgate.net/publication/339272195_Development_of_submarine_cable_hydrodynamic_loads_calculation_program_using_MATLAB

For simple PM, please check pages 6 to 8:

You can do all you mention with the Tsunami-HySEA code (https://edanya.uma.es/hysea/). You can download a open source version of the code (not allowing nested grids) at: https://edanya.uma.es/hysea/index.php/download. And you can find extensive references at: https://edanya.uma.es/hysea/index.php/references

Oceanic waves (swell) generate in areas of persistent stormy and high wind speeds (wave factories) and propagate out from there, coalescing one with another during thousand of kilometers, finally reaching the nearshore of coastal waters as almost regularly spaced (here in SW Australia, 12-14 seconds, extremely long) packs of 2-5 similar waves, refracting against he seabed and breaking or surging or spilling on beachfaces.

Swell, is the oceanic expression of an aeolian (wind) process.

The Coriolis Effect, like wind and cyclones paths, has an impact on swell propagation across big distances, but "vibrations" of Earth, on swell do not have impacts.

Earthquakes, vulcanic eruptions and submarine landslides certainly cause anomalous waves (Tsunamis), but do not modify swell.

In conclusion, swell, as far as I know, is not affected by earthquakes.

Cheers

Nick

Are you interested in theoretical aspects? If yes, decouple your system in the form of a dinNPDE. Apply preferably numerical simulations to see the wave amplitude behaviours, and so forth. Have a needful comparison with the latest reports on it.

take a look to this link:

http://www.coastalhazards.org/oceanlyz.html

This paper may help in your research Direct Formula to Compute Wave Height and Angle at Incipient Breaking, JWPCE, ASCE

Dear Satish,

I have the following opinion :

The motion of a submarine could be similar to the propagation of an internal wave. The conservation of mass muss be zero for a wave perturbation in the vertical integration. In the case of a submarine you have mass transport (the submarine ) and the surface will be affected.

Regards

Chris, a bit of friendly advice. You talk about WEC, but no where in your post do you mention what it stands for! Avoid acronyms.

WEC: Word Endurance Championships, World Energy Council, White Edge Crack, Washington Electric COOP, and the list goes on

Interested

There are two type of boundary cond. @ wall : "No Slip" & "Free Slip"

@ Bottom if you consider the " penetration " you might have vertical velocity, otherwise the perpendicular velocity would be zero; Horizontal Velocity is also the same as wall, "No Slip" with exponential profile in water column & "Free Slip"

@ free surface for 3D model you can use the VOF (Volume of Fluid) technique for better modelling the shape of the interface.

@ Upstream you could add wave maker through "piston" type or "plunger or paddle" type with relevant amplitudes, frequencies, & equations ...

@ Downstream it is better to assume a "low slope beach" to damp the energy, otherwise the channel should be long enough to avoid the impact of the "Reflection"

The most common examples of vortical structures are found in classical fluids; at the laboratory scale, we can mention

In the rotating stratified fluids in geophysical systems, we have a multitude of vortices at different scales; they include

The main characteristic of all these structures is that they do not keep their identity for a very long time, the main exception being perhaps the red spot of Jupiter which has preserved its integrity over the last few hundred years.

The completely new reality of vortex systems is in quantum fluids where they can last indefinitely.

On a larger scale, in space, practically all forms of matter organization come in the form of swirls with the most spectacular examples provided by rotating galaxies. It is fairly easy to conclude that the vortex movement is ubiquitous in all physical systems, from the smallest to the largest. There are even some attempts to connect the scales proposed in the framework of a Cantorian Superfluid Vortex hypothesis; these attempts are very similar, in many respects, to Lord Kelvin's old hypothesis explaining atoms as vortex structures.

For an in-depth discussion of all these fascinating topics, please see a very interesting article by Frank Wilczek entitled: "Beautiful Losers: Kelvin's Vortex Atoms". The text is available at:

You shoud add function ovject to your controlDict in order to read forces etc.

From the forces probably you can calc what u need.

Franco

I think your interest to examine these temperature and salinity density/stability ratio on the coastline rather on the open water. If so, I suggest you look in other factors i.e., tidal chandes, local current circulation and bathymetry. 

These elements are affected local dwillers in many ways i.e., induce spawning

Hi Widitha

The shunt load is required for numerical stability of the model and should be set to 5% of the nominal value of the machine. In your case, you have a 1MVA machine so you should set the shunt load at 50kW.

The series load is set by you, according to your application. If you don't know what you are doing, I would suggest to set it to 80% of nominal power.

Hope this answer your question

Luc-André

I had generated some sketches for the air-entrainment, bubble formation and buoyant degassing processes occurring during plunging breaking for my review article.

Here's a link to the paper. I hope this helps. Best regards. 

Are you using a ramp to initialize the flow? From your image I guess that an abrupt flow initialization may give this effect.

Try to check also your timestep and CFL during the simulation as well as the discretization around the free surface.

I do not think we know what is happening at 70 m/s... The sea is white, the air is full of spray...

Thank you Fabrice Ardhuin and Nguyen Thanh Luan...

You will find some info on Sentinel 1 wave mode here ... http://oceanwavesremotesensing.ifremer.fr/

As for the level 2 access, just ask Alexis mouche <alexis.mouche@ifremer.fr> or Romain Husson at CLS.

Hi guys,

the latest hindcasts are at

if you are looking at rectangular grids, yes the latest reference is Rascle & Ardhuin (2013). For the triangle-based grids, there are extra coastal effects described in Roland and Ardhuin (Ocean Dynamics 2014) :

And if you are interested in infragravity waves

the proper paper would be Ardhuin et al. (Ocean Modelling 2014)

Thanks to all. I finally found an answer in Cole et al. (JGR 1998): "Cyclic loading and creep response of aligned first-year sea ice" which is generally consistent with Wadhams (JGR 1973), in proposing a reduced B coefficient for creep. This is now in version 5.10 of WAVEWATCH III (to be released in a few months) ... and was used for this paper:

But yes it is in general a function of ice temperature and thickness and floe sizes are very important parameters too. 

TUNAMI is code written by Prof. Immamura. It has TUNAMI N1, N2, N3 and F1, F2. N stands for  near field and F stands for far field. Code is available online. YOu may refer the following document:

Not sure about 1KHz, but if you wanted to callibrate before casting them, controll environment is the best as Mr jf Argentino suggested. And as for more the manufacture information must be kept in mind for accuracy n resolution for those sensor. 

You can export a sample .dfs2 file to ASCII to see the structure of header, body, etc.

Something like this:

--------------------------------

"Title" "File Title"

"Dim" 2

"Geo" "LONG/LAT" 46 36 0

"Time" "EqudistantTimeAxis" "2015-01-01" "00:00:00" 848 21600

"NoGridPoints" 73 97

"Spacing" 0.125 0.125

"NoStaticItems" 0

"NoDynamicItems" 3

"Item" "u" "Wind speed" "m/s"

"Item" "v" "Wind speed" "m/s"

"Item" "mslp" "Pressure" "hectoPascal"

NoCustomBlocks 1

"M21_Misc" 1 7 0 -1E-030 -900 -99 -1E-030 -1E-030 -1E-030

"Delete" -1E-030

"DataType" 0

"tstep" 0 "item" 1 "layer" 0

2.652323 2.653296 2.673731 2.694167 2.715089 2.735525 2.755961 2.776396 2.797319 2.801698 2.798292 2.795372 2.791966 2.788561 2.785641 2.782235 2.778829 2.771531 2.763746 2.756447 2.749149 2.741850 2.734065 2.726767 2.712657 2.684922 2.657675 2.629941 2.602207 2.574472 2.546738 2.519491 2.484945 2.446993 2.409041 2.371575 2.333623 2.295671 2.257719 2.219767 2.215388 2.211982 2.209063 2.205657 2.202251 2.199332 2.195926 2.200305 2.224633 2.248961 2.273289 2.297618 2.321946 2.346274 2.370602 2.404662 2.445533 2.485918 2.526789 2.567174 2.608045 2.648917 2.689302 2.753528 2.819701 2.885873 2.952046 3.018219 3.084878 3.151051 3.219656 3.297020 3.373897

.

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.

------------------------------

Write your code via MATLAB/FORTRAN or any program languages you're able to use

Hi Georges:

At high winds (above 25ms-1) the sea surface roughness saturates hence the Charnock coefficient becomes constant. This does not mean that for higher winds  the momentum flux becomes constant because it increases as the wind speed squared. A good reference on surface roughness saturation is the paper by Donelan et al. 2004 published in Geophys. Res. Lett. Measurements in hurricanes have shown a decrease of drag coefficient at very strong winds this topic is discussed in papers by Emanuel, Soloviev and others.

Regards

Héctor

Please see the report arXiv:1503.04313v1.pdf

You could try Nansat (https://github.com/nansencenter/nansat). Should at least get you a bit further than just reading the data. It works quite well for ASAR and Radarsat-2, and also Sentinel-1 should be ok.

Hi,

There are a few oceanography and climate libraries for python. You should check a list like this:

1) http://oceanpython.org/links/

2) http://www.imr.no/~bjorn/python/links.html

As for extracting the exact parameters you're requesting I would advise checking scientific literature (since I don't know how to do it). A quick google search for "RISAT-1 ocean waves" revealed this article:

You can request the full article here in research gate. I'm sure a more extensive search would reveal a lot more info on the subject.

Best of luck.

Dear Paul,

The definition is totally irrational. I avoid using it because I find it wholly misleading. Using Hs as a reference is also irrational but less so since nearly everybody seems to believe it with religious zeal, and it has become an unfortunate unavoidable fixture in oceanography and ocean engineering that is impossible to get rid of and replace with the rms surface displacements as the more logical choice. To an outsider well informed in statistics and stochastic processes, this will look a rather nonsensical parameter for scaling various features of the sea-surface elevations.

There are more rational ways for describing wave occurrences that do not seem to follow expectations defined in terms of a reliable wave-height model. These are basically outliers that can be defined on a logical basis as a joint event that a wave height several times larger than the surface rms occurs, and it does so more frequently than what we predict from a well-established wave-height frequency distribution. In other words, the definition must include a threshold representing a relatively large magnitude as well as some higher rate of occurrence. Otherwise, wave-heights satisfying thresholds such as H//Hs > 2-3 or more are not necessarily abnormal since they are predicted by the Gaussian model, obviously with very low frequencies of occurrence.

An apparent difficulty with the alternative definition implied here is that how one decides on a relative threshold magnitude that would be of importance in theory and practice. My experience is that even the so-called abnormal waves do not violate the Miche-Stokes type upper bounds. Relatively low or small waves do, but we are not interested in these in the present context. Given the spectrum, the largest wave that we might observe based on the Gaussian or some non-linear theory is that implied by this upper bound. If one uses the spectral average period (T01) associated with the largest waves in a sea state, the period of the largest ones seem to converge to a value 1-1.25 * T01 approximately, depending on the frequency bandwidth. The corresponding upper limit wave height then follows immediately from the Miche-Stokes bound. That is one possible clue to the threshold magnitude needed. Consequently, the relative frequency of that threshold is easily  estimated from the theoretical wave-height frequency curve. If the wave height and associated occurrence frequency of a large wave actually observed exceeds the two thresholds both noticeably, say about 5-10% or so, then one can contemplate if the observed wave is an abnormal occurrence. 

The bigger dilemma is that there is presently no way for experimentally verifying the existence of these "abnormal waves" under oceanic conditions. They seem to be isolated occurrences observed as outliers in some relatively short wave record, but it is ignored that the wave field where that record comes from actually contains zillions of other waves. Fixed-point observations are archaic and simply misleading for extremes to begin with in realistic seas characterized with a directional wide-band spectral content. So, what is needed is much larger spatial-temporal observations of the wind-disturbed sea-surface over long intervals of time. That has not become a routine yet. Numerical and experimental simulations in wave tanks do not explain what might be happening in the ocean. There is a lot more to discuss on the general topic, but enough now.

Best regards...Aziz

... thanks a lot!

I think Christian's answer covers a lot of ground.  Is the wave a freak because it is different from the wave field it is in, is it an extreme wave (which is the public idea) or is it a wave that produces unusual forces/motions/effects.  All are 'freaks' in some way and size does not really matter :)

A real 'freak' would be defined as inexplicable in terms of existing theoretical paradigms.

If the question is about defining a probability in philosphical terms then maybe we are into the idea of 'surprise' - I think there's a very old book by Spanner - it was new when I was young.

Or there is a field of study that deals with the probability of events that never happen where the boundary limit is estimated by the duration within which nothing has been observed.

I am a believer in the use of NLSE for optical phenomena not for surface waves.  There is some work on the importance of transverse shear flow in generating these.  When you say "goes off" do you mean that the wave is suddenly dissipating?   I did a little calculation recently that gives the energy of such a bound wave group as borrowed from the surface shear energy so the vanishing of the shear allows the wave to spread into the spectral components and simply become lower and wider.  

I've been perplexed by the state of this field for a while.  I thought I would visit the topic while studying hydrodynamics of quantum gases to get some classical background but I found a lot of enduring superficial analysis and inconsistent assumptions.  I don't claim to be certain of the answer.  I wrote a series of papers that I recently sent off.  Tell me if they address the general topic you are asking about in any meaningful way.  

The nonhydrostatic effects are important when the vertical acceleration is non-negligible. Boussinesq (1872) describes mathematically this kind of equations when the vertical velocity component is included in the integrated motion equations. In the literature, contributions related to barotropic and homogene water have been published in the literature in the last 50 years ( e.g. Peregrine 1967; Abbot et. al. ,1978; Hauguel 1980; Shapper, 1986).

Boussinesq J., 1872. Theory des ondes et des remous Qui se propagent le long d?un canal rectangulaire horizontal, en communiquant au liquide contenu dans ce canal des vitesses sensiblement pareilles de la surface au fund. J. Math. Pures Appl., vol. 17, pp. 55-108.

Abbot M.B., Peterson H.M., Skoovgaard, 1978. On the Numerical Modelling of Short Waves in Shallow Water. Journal of Hydraulic Research, vol. 16, pp. 173Peregrine D.H., 1967. Long waves on a beach. Journal of Fluid Mechanics, vol. 27, pp. 815-827.

Shapper H., 1986. Ein Beitrag zur numerischen Berechnung von nichtlinearen kurzen Flachwasserwellen mit verbesserten Differenzenverfahren. Report No. 21, Institut fuer Stroemungsmechanik und Elektronischen Rechnen im Bauwesen, Universitatet Hannover. -203. 

To play around with data this MATLAB toolbox is a good base:

MACE toolbox from Nobuhito Mori:

You might also have look here for Nobuhito Mori.

Greetings

Please try to see relevant papers by Dr. Ir. Johan Weichers. He is one of the pioneers in this field. You can also see some works by Prof. Grant Hearn. These works are all done in late 80s and early 90s.

wgrib, which is available from NCEP is another useful tool for dumping grib to different formats.  Here are some tricks:  ftp://ftp.cpc.ncep.noaa.gov/wd51we/wgrib/tricks.wgrib

Arno: I don't know who described the CMB as homogeneous, but I have here on my bookshelf Weinberg's 1972 book, Gravitation and Cosmology, which has an entire chapter devoted to the topic of the CMB, including a detailed discussion of its fluctuations and anisotropies, along with whatever scant early observational data was available at the time.

Then, as early as 1983, there was already a space-based (Soviet) experiment producing a whole-sky CMB map clearly showing the anisotropy due to the Earth's motion and smaller fluctuations (https://web.archive.org/web/20130331094338/http://epizodsspace.airbase.ru/bibl/nauka-v-ussr/1992/vzglad.html). The experiment was sufficiently sensitive to detect a quadrupole moment (https://en.wikipedia.org/wiki/RELIKT-1).

Ten years ago, the WMAP satellite was already collecting data for three years. Indeed, their first data release took place one year earlier (see, e.g., http://lambda.gsfc.nasa.gov/data/map/Tegmark/toh_wmap_wiener.jpg). So the suggestion that "ten years ago [...] background radiation was described as homogeneous" seems to me strongly contradicted by the actual, well-documented history of the subject. Indeed, I am not aware of any serious suggestion in physical cosmology that the CMB would be homogeneous; on the contrary, it was understood very early on that the temperature fluctuations of the CMB would be strongly correlated with density fluctuations of matter in the early universe. By 1972, when Weinberg's famous book was published, this was well-established science.

Just to be clear, I like weird ideas. I worked on a few of them myself. But it is not enough for an idea to be weird... it also has to show agreement with observation, be self-consistent, and it must be an improvement over existing ideas in terms of its predictive power. And while the inertia of the "mainstream" and the resistance of a mediocre "establishment" to new thoughts can be annoying at times, all too often, when maverick ideas fail on these counts, their supporters tend to blame some "mainstream" conspiracy instead of doing the right thing, namely revising or discarding a hypothesis that is proven to be untenable.

One of the other possible answer could be that Boussinesq equation can model nonlinear waves but Mildslope equations can model only linear waves.

See Apotsos et al. [JGR 2008] (http://onlinelibrary.wiley.com/doi/10.1029/2007JC004514/abstract) where they analyzed alongshore setup and flow variability in the surf zone.

Hi José, the reference is: Constantin, Adrian, and Joachim Escher. "Particle trajectories in solitary water waves." Bulletin of the American Mathematical Society 44.3 (2007): 423-431.

I actually double checked in the Chawla et al. paper (in press in Ocean Modelling) and there is a clear creep up of the 80 to 99 percentiles of the CFSR wind after 2006, not of the mean.