Open channel wave BC use

alexie · June 5, 2010, 21:11

Hi, im trying to model a propagating deep water wave in a flume, and have managed to set up an inlet BC which generates waves at the air/water interface, but these seem to dissipate after about 2 wavelengths of travel down the flume?
I'm currently using and explicit VF scheme, geo-reconstruct, 1st order implicit time scheme, and changing between 1st or 2nd order advection schemes doesn't seem to make a difference.
I have however been using a stretching mesh which is highly resolute at the interface and stretches up and down, and was wondering if this has some effect for explicit VF schemes as they are generally difficult to solve with more comples mesh geometry.

If anyone has any tips on using that wave BC it would be greatly appreciated!

gatzhamm · February 24, 2011, 09:38

Hi Alexie,

I basically have the same problem, and after a lot of trying around with different spatial and temporal resolutions, and boundary conditions at the outflow, I kind of start to believe that there is no nice solution to the decaying of waves. Also when using non-visicid flow, the waves decay much too fast.

Could you find a solution to that problem already?

Best regards,
Bernhard

Ayuba · March 8, 2014, 09:04

You could go to the fluent user guide on page 1288. This talks about the Number of wavelengths to damp which is set to 2 by default and also the damping resistance can be played with. I hope this helps and if it does it might solve this problem before I get to it. Cheers.

danielfc · October 17, 2014, 14:37

I know that thre is already a long time since you guys posted these threads, bu I am solvind a wave propagation with no problem. The wave dissipation seems to be essentially a discretization (spatial and temporal) issue. Now I am working with deltaX = 2.5% wavelength, deltaY = 5% wave height and deltat = 0.2% wave period. With those parameters I could represent nicely waves measured in the laboratory.

June 5, 2010, 21:11	Open channel wave BC use	#1
alexie New Member Alexie Join Date: Jun 2010 Posts: 1 Rep Power: 0	Hi, im trying to model a propagating deep water wave in a flume, and have managed to set up an inlet BC which generates waves at the air/water interface, but these seem to dissipate after about 2 wavelengths of travel down the flume? I'm currently using and explicit VF scheme, geo-reconstruct, 1st order implicit time scheme, and changing between 1st or 2nd order advection schemes doesn't seem to make a difference. I have however been using a stretching mesh which is highly resolute at the interface and stretches up and down, and was wondering if this has some effect for explicit VF schemes as they are generally difficult to solve with more comples mesh geometry. If anyone has any tips on using that wave BC it would be greatly appreciated!

March 8, 2014, 09:04	Numerical Beach setting might work. Even though I haven't tried it yet	#3
Ayuba New Member Ayuba Jonathan Join Date: Mar 2014 Posts: 2 Rep Power: 0	You could go to the fluent user guide on page 1288. This talks about the Number of wavelengths to damp which is set to 2 by default and also the damping resistance can be played with. I hope this helps and if it does it might solve this problem before I get to it. Cheers.

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February 24, 2011, 09:38		#2
gatzhamm New Member Join Date: Feb 2011 Posts: 1 Rep Power: 0	Hi Alexie, I basically have the same problem, and after a lot of trying around with different spatial and temporal resolutions, and boundary conditions at the outflow, I kind of start to believe that there is no nice solution to the decaying of waves. Also when using non-visicid flow, the waves decay much too fast. Could you find a solution to that problem already? Best regards, Bernhard

October 17, 2014, 14:37		#4
danielfc New Member Join Date: Nov 2013 Posts: 11 Rep Power: 13	I know that thre is already a long time since you guys posted these threads, bu I am solvind a wave propagation with no problem. The wave dissipation seems to be essentially a discretization (spatial and temporal) issue. Now I am working with deltaX = 2.5% wavelength, deltaY = 5% wave height and deltat = 0.2% wave period. With those parameters I could represent nicely waves measured in the laboratory.