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WAVE TANK star-ccm+ . wave height dampens. WHY?

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Old   August 4, 2012, 06:55
Default WAVE TANK star-ccm+ . wave height dampens. WHY?
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muhsin
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HI all.
I am trying to simulate wave tank with dimensions [ 26m*.6m*1m = L*B*H ]

Boundary conditions:
1. same as DFBI tutorial
2. Velocity inlet [ wave field function], [bottom, sides and end] as walls and top as pressure outlet.[atmospheric pressure]

In both conditions I am not getting proper wave height at different positions from velocity inlet.
It seems that wave is getting damped as it progresses. NO VOF WAVE DAMPING WAS ACTIVATED.

You can see in the images below




this is for IMPLICIT UNSTEADY time step=.01s
When i use time step of .001s results are better but even then wave dampens as it progress.
cut section through wave tank

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Old   August 10, 2012, 18:50
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Brendan Smoker
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My first thought is that it is a meshing issue. Often a coarse mesh will damp out waves. Thus, it is important to have a fine enough mesh from the inlet to the area of interest in order to maintain the full size of the wave. Additionally, some mesh size and time step combinations can cause odd issues with the free surface such as unwanted damping and wave reflections.
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Old   September 5, 2012, 06:18
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Henry Arrigo
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BrenS is right. One good remedy is to refine the mesh in the vicinity of the free surface.
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Old   October 9, 2012, 13:24
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Bilal Zeidan
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hi! how did things go with you . I am trying simulate a wave tank so if you can send me a tutorial or any link that can help. I am still new to cfd so please any help will be appreciated.
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