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Incompressible Navier Stokes

Posted 2009年11月26日 GMT-5 13:10 Computational Fluid Dynamics (CFD) 13 Replies

edward smith
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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.
13 Replies Last Post 2015年7月28日 GMT-4 18:35
Edwin Insuasty
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Posted: 2 decades ago 2009年12月1日 GMT-5 22:55
I've used general forms to describe Navier Stokes equations.... it's quite easy...

check this files

sts.bwk.tue.nl/hamlab/readers/COMSOL_SFunction.zip

have fun!
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!
edward smith
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Posted: 2 decades ago 2009年12月2日 GMT-5 10:54
Thank you. I'll try out the comsol files. Will they run undependently of the mat;lab files?
Regards
TedSmith
Thank you. I'll try out the comsol files. Will they run undependently of the mat;lab files? Regards TedSmith
edward smith
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Posted: 2 decades ago 2009年12月2日 GMT-5 11:33
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
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
Edwin Insuasty
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Posted: 2 decades ago 2009年12月3日 GMT-5 17:02
Of course... here is the model equations...
Of course... here is the model equations...
edward smith
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Posted: 2 decades ago 2009年12月3日 GMT-5 17:21

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

[QUOTE] Of course... here is the model equations... [/QUOTE] 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
Jim Freels mechanical side of nuclear engineering, multiphysics analysis, COMSOL specialist
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Posted: 2 decades ago 2009年12月3日 GMT-5 22:02
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 !
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 !
Ozgur
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Posted: 2 decades ago 2009年12月4日 GMT-5 19:00
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
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
Omar Al-Abbasi
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Posted: 2 decades ago 2009年12月8日 GMT-5 05:05
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 :-)
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 :-)
edward smith
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Posted: 2 decades ago 2009年12月8日 GMT-5 13:50
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
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
Edwin Insuasty
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Posted: 1 decade ago 2009年12月13日 GMT-5 13:56
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
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
c_h_r_i_s
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Posted: 1 decade ago 2010年1月8日 GMT-5 15:48
Just wanted to say thanks for the posts. I found the comments and files exceedingly helpful!
Just wanted to say thanks for the posts. I found the comments and files exceedingly helpful!
Jim Freels mechanical side of nuclear engineering, multiphysics analysis, COMSOL specialist
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Posted: 1 decade ago 2010年1月9日 GMT-5 14:21
Try this example right off the COMSOL model exchange:

www.comsol.com/community/exchange/62/
Try this example right off the COMSOL model exchange: http://www.comsol.com/community/exchange/62/
Mohammad Rahman
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Posted: 9 years ago 2015年7月28日 GMT-4 18:35
Hi,

Thank you for sharing the link. Unfortunately the link is not working anymore. Could you please share it again?
Hi, Thank you for sharing the link. Unfortunately the link is not working anymore. Could you please share it again?

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