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Mass Balance Tracking

Posted 25.02.2011, 00:37 GMT-5 Fluid & Heat, Computational Fluid Dynamics (CFD), Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4.0a 2 Replies

Ranjeeth Naik
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Hello,

I am trying to solve a rectangular domain fluid flow and heat transfer problem (please look at the attached figure).
I had following questions:

1. The problem was solved using Comsol 4.0a with “pressure-point constraint” of 0 Pa at point “c”. The “Laminar Flow” and “Heat Transfer” models were used. The stationary solver gave a converged solution. However on checking the mass balance for the boundaries a mass deficit was observed.

Is there a method to ensure that the mass, momentum and energy balances are satisfied accurately during the process of solving? And also can this be tracked/ monitored during the process of solving? How can the accuracy be improved?

2. Now if the same problem is solved using Comsol 4.0a with “pressure-point constraint” of 0 Pa at point “a”, the stationary solver does not solve. How can this problem be resolved?

Also I am using a free triangular mesh with "extremely fine" size.

Thank You,
Ranjeeth
2 Replies Last Post 04.03.2011, 16:16 GMT-5
Ranjeeth Naik
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Posted: 1 decade ago 04.03.2011, 11:30 GMT-5
does anyone know how to do it?

Thanks,
Ranjeeth
does anyone know how to do it? Thanks, Ranjeeth
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 04.03.2011, 16:16 GMT-5
Hi

I'm not sure its the pressue point, have you noticced that you have NOT coupled the velocity field from the fluid flow to the HT (change in the Model Input tab). And if you have a fluid, then you should use HT in fluid thermal physics and NOT SOLID

currently you have only conduction in your results, no fluid flow /(I'm running v4.1 so there might be differences as v4.0 was not really ironed out, particularly not for CFD

--
Good luck
Ivar
Hi I'm not sure its the pressue point, have you noticced that you have NOT coupled the velocity field from the fluid flow to the HT (change in the Model Input tab). And if you have a fluid, then you should use HT in fluid thermal physics and NOT SOLID currently you have only conduction in your results, no fluid flow /(I'm running v4.1 so there might be differences as v4.0 was not really ironed out, particularly not for CFD -- Good luck Ivar

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