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More services...Incompressible Navier Stokes
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12 Replies
Last post: January 9, 2010 7:21pm UTC
November 26, 2009 6:10pm UTC
Incompressible Navier Stokes
I would be interested to communicate with anyone who has used COMSOL to implement Navier-Stokes by using either the PDE or General forms, rather than the built-in Navier Stokes models.
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December 2, 2009 3:55am UTC in response to edward smith
Re: Incompressible Navier Stokes
I've used general forms to describe Navier Stokes equations.... it's quite easy...
check this files
http://sts.bwk.tue.nl/hamlab/readers/COMSOL_SFunction.zip
have fun!
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December 2, 2009 3:54pm UTC in response to Edwin Insuasty
Re: Incompressible Navier Stokes
Thank you. I'll try out the comsol files. Will they run undependently of the mat;lab files?
Regards
TedSmith
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December 2, 2009 4:33pm UTC in response to Edwin Insuasty
Re: Incompressible Navier Stokes
Thanks again for the files. They mph files work fine. Not used the MATLAB interface yet so can't follow the M files yet.
I can't understand the problem you are trying to solve. Do you have any documentation that shows how you have converted the N-S equations to the general form? That would be very helpful. I want to obtain pressure from this solution and also want to restrain it from becoming negative.
Regards
Ted Smith
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December 3, 2009 10:02pm UTC in response to edward smith
Re: Incompressible Navier Stokes
Of course... here is the model equations...
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December 3, 2009 10:21pm UTC in response to Edwin Insuasty
Re: Incompressible Navier Stokes
Of course... here is the model equations...
Thank you Edwin. I am going on a course next week on COMSOL so will learn a lot more! I had not realised that you must specify the momentum and continuity equations. The whole process seems to be much more complex than ANSYS and requires and understanding of vector mechanics (on which I am weak!). Why did you choose COMSOL?
Regards
Ted
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December 4, 2009 3:02am UTC in response to edward smith
Re: Incompressible Navier Stokes
Follow up to your last question, but reply to your original question. One cannot solve a general set of equations with ANSYS, only what they provide you. Naturally, solving your own set of equations becomes more difficult. Hence, the reason some people prefer not to have so much power !
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December 5, 2009 12:00am UTC in response to Edwin Insuasty
Re: Incompressible Navier Stokes
Edwin,
I am just curious. Is there a reason why you didn't use one of COMSOL's built in multiphysics coupling models (as in fluid/thermal interaction in the COMSOL base module)?
Thanks,
Ozgur
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December 8, 2009 10:05am UTC in response to Edwin Insuasty
Re: Incompressible Navier Stokes
Grupo ...Thanks a lot for the model.
I tried to do the same thing long time ago but I did not manage how to do so.
Now I know how :-)
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December 8, 2009 6:50pm UTC in response to Edwin Insuasty
Re: Incompressible Navier Stokes
this has really helped. In my problem, I have a moving wall (no-slip, u1=U, u2=0) , two outlets (at zero pressure, i.e. u3=0) and a stationary, no-slip wall (u1=0,u2=0) .
How would you put in the bc's in the three equations?
By the way, why did you use 2 separate pdes for the 2 momentum equations, rather than 1 with 2 dependent variables?
Regards
Ted
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December 13, 2009 6:56pm UTC in response to edward smith
Re: Incompressible Navier Stokes
Hi .. I'm glad to hear this files were useful for you, the main advantage of the pde general form is that you have complete power on the way you implement your pde's system.... I'd rather to implement 2 separate momentum equations because that's the way my model was defined, if you check my equations, those are not defined as tensors, those are defined as scalar equations....of course, you are free to implement your model equations whatever you want..
Kind regards
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January 8, 2010 8:48pm UTC in response to Edwin Insuasty
Re: Incompressible Navier Stokes
Just wanted to say thanks for the posts. I found the comments and files exceedingly helpful!
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January 9, 2010 7:21pm UTC in response to edward smith
Re: Incompressible Navier Stokes
Try this example right off the COMSOL model exchange:
http://www.comsol.com/community/exchange/62/
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