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how to polt surface elevation over time at a fixed point ?

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Old   July 12, 2012, 14:34
Default how to polt surface elevation over time at a fixed point ?
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Teemo
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Hello,

I would like to plot a graph about wave pattern at a fixed point over time in paraview, but I dont know how to trace the free surface elevation, is there any way to do that without other 3rd party software?

Regards,
T
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Old   July 12, 2012, 17:55
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Bernhard Gschaider
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Hello,

I would like to plot a graph about wave pattern at a fixed point over time in paraview, but I dont know how to trace the free surface elevation, is there any way to do that without other 3rd party software?

Regards,
T
Define 3rd party software? And does it have to be paraview?

If I understand you right with "fixed point" you mean coordinates ( x , y ) and you want to find the z so that ( x , y , z ) is on the water surface and then you want to plot z(t), right?

This has been described on slide 135ff of http://www.openfoamworkshop.org/6th_...der_slides.pdf

Disadvantage is of course that swak is ThirdParty-Software. Advantage is that you can do this during the simulation and therefor get a finer temporal resolution than just taking the written times (but of course you can do that kind of calculation after the simulation with swak)
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Old   July 13, 2012, 07:17
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Hi,
Thanks for ur reply, sry for the bad description, I would like t plot the wave elevation z (t) at fixed (x, y) but I dont know how to trace the free surface.

is there any way to achieve it in post-processing, for example, any function in paraview since it take too much time to re-run the case
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Old   July 13, 2012, 07:26
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Bernhard Gschaider
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Quote:
Originally Posted by Teemo View Post
Hi,
Thanks for ur reply, sry for the bad description, I would like t plot the wave elevation z (t) at fixed (x, y) but I dont know how to trace the free surface.

is there any way to achieve it in post-processing, for example, any function in paraview since it take too much time to re-run the case
Paraview I don't know, sorry (maybe by writing your own filter in Python with ProgrammableFilter). With funkyDoCalc you could do it in swak though
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Old   July 14, 2012, 14:13
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Björn Windén
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Hi.

I probe a number of points along a vertical line at (x,y) and then, using the values of alpha along that line, work out (using linear interpolation between the first point where alpha>0.5 and the last point where alpha<0.5) where alpha=0.5.

I do this as a function object but I guess you could use probesDict and process it afterwards as well.

//Björn
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Old   July 20, 2012, 07:45
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Hi Bjorn,

Thanks for you reply, could you send you a detailed work that how you achieve this (Teemo881123@gmail.com) ? I am new to OpenFOAM so I dont quite understand what is probesDict

Many thanks,
T
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Old   July 20, 2012, 09:43
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Hi,

I suppose you used interFoam? In that case, make a contour of places where alpha = 0.5.
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Old   July 20, 2012, 09:52
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hi Flowris,

I used waveFoam,based on interFoam, to simulate a wave tank.
In paraview, I made a contour where alpha=0.5, but it only shows the free surface, how can I get the Y value (vertical) VS time at a fixed x and z point?

Thanks,
T
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Old   July 20, 2012, 10:49
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So first you make the contour plot, and then with the calculator, you color this surface using scalars > coordsY.
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Old   July 21, 2012, 08:05
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And to get the data from that contour you could either write a python script for the programmable filter in paraview or (this is a guess) you can have a look at the datapoints of the contour in a tabulated manner.
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