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BC at the entrance and exit of a wave tank

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Old   September 1, 2009, 08:50
Exclamation BC at the entrance and exit of a wave tank
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Hello!

Im simulating waves and wind in a tank. I have tried different options for the Boundary conditions for preventing the outflow at the entrance and inflow at the exit ( I have to avoid reflections). I think perhaps the best option is to put openings at both sides, having the velocity expressions at the entrance and a pressure option at the exit.
Could kindly anyone tell me which could be the best option for the pressure at the exit to avoid inflow?

Thank you in advance

Last edited by cfxmar; September 1, 2009 at 08:56. Reason: Note: I cannot put an outlet at the exit because the tank is too much long
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Old   September 1, 2009, 18:48
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Waves on a free surface inherently involve a region of backwards flow so you can't eliminate backflow. If you want a non reflecting boundary have a look at the new non-reflecting boundary feature in V12 (I have never used it so cannot say much about it) OR put a ring of very coarse elements around your domain connected to the main domain by a GGI. The very coarse mesh will damp out the waves and allow you to use simpler boundary conditions. Again I have never tried this either but I have read journal articles where it has been done.
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Old   September 1, 2009, 23:00
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Hi Mr. CFXsea,

Is something like that?

http://rapidshare.de/files/48267869/Canal1.rar.html . A good site to start studying is http://seam.ustb.edu.cn/UploadFile//...2040742250.pdf . Im also a beginner as you. Good lucky, Sir.

with kind regards,

Rogerio.

Quote:
Originally Posted by cfxmar View Post
Hello!

Im simulating waves and wind in a tank. I have tried different options for the Boundary conditions for preventing the outflow at the entrance and inflow at the exit ( I have to avoid reflections). I think perhaps the best option is to put openings at both sides, having the velocity expressions at the entrance and a pressure option at the exit.
Could kindly anyone tell me which could be the best option for the pressure at the exit to avoid inflow?

Thank you in advance

Last edited by rogbrito; September 2, 2009 at 07:47.
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Old   September 2, 2009, 03:25
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Thank you, Glenn. What is a GGI?...I use CFX-Mesh, I dont know if it is something related to another software to mesh the geometry.
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Old   September 2, 2009, 03:38
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Hello Rogerio. I dont mind to show the problem Im trying to solve. I have told yet Its a tank of waves mixed with wind blowing. Im trying to calculate the forces generated by waves and wind on a pile.

P.S Anyway, Im Miss...
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Old   September 2, 2009, 05:52
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A GGI is a general grid interface. It allows you to join non-contiguous meshes together easily. It is also used to join sections of mesh which move relative to each other such as rotating machinery. Have a look at the rotor/stator example in the tutorials for how GGI's work.
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Old   September 4, 2009, 03:10
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Sorry Rogerio but I couldnt open the archive as it expired in a short time:

http://rapidshare.de/files/48267869/Canal1.rar.html

Could you please put it on line again?

About the documentation you told me, thanks, but I have read the tutorials yet.

If you are solving the same problem, I hope we could help each other.

Thank you
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