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Transport of dilute species module
Posted 10.02.2015, 06:32 GMT-5 3 Replies
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Respected Sir,
I am attaching my .mph file.It is working well when a>=1.For my case a=0.5 it is showing error.
Here 'a' is the power of the concentration.
I kindly request you to help me out with this problem.
Regards
I am attaching my .mph file.It is working well when a>=1.For my case a=0.5 it is showing error.
Here 'a' is the power of the concentration.
I kindly request you to help me out with this problem.
Regards
Attachments:
3 Replies Last Post 10.02.2015, 09:12 GMT-5
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Posted:
10 years ago
Hi
I just remembered that you have to write the flux BC as
-kr*c1*(c2/C0+eps)^a/(1+K*(c1/C0))
"eps" is a machine constant, floating point accuracy, a very small number, 2^-52. Look at help with "eps".
Another thing: You do need two separate nodes of "Transport of Dilutes Species", you can have both variables c and c2 in the same node, just put the number of variables 2.
I usually do so that I first calculate the laminar flow at steady-state in its own Study, i.e. disabling all the other physics; let's call this Study 1. Then I calculate the rest of the physics in another Study 2, disabling Laminar Flow, and in the menu "Values of variables not solved for" I select "Study 1, Stationary". In the Transport of Diluted Species node I choose the velocity field "spf", not user defined u and v. Now Comsol understands that I am using the velocity field of the Laminar Flow node for which Comsol gives the default identifier "spf".
I tried with a = 0.5 with no problems.
Good luck
Lasse
I just remembered that you have to write the flux BC as
-kr*c1*(c2/C0+eps)^a/(1+K*(c1/C0))
"eps" is a machine constant, floating point accuracy, a very small number, 2^-52. Look at help with "eps".
Another thing: You do need two separate nodes of "Transport of Dilutes Species", you can have both variables c and c2 in the same node, just put the number of variables 2.
I usually do so that I first calculate the laminar flow at steady-state in its own Study, i.e. disabling all the other physics; let's call this Study 1. Then I calculate the rest of the physics in another Study 2, disabling Laminar Flow, and in the menu "Values of variables not solved for" I select "Study 1, Stationary". In the Transport of Diluted Species node I choose the velocity field "spf", not user defined u and v. Now Comsol understands that I am using the velocity field of the Laminar Flow node for which Comsol gives the default identifier "spf".
I tried with a = 0.5 with no problems.
Good luck
Lasse
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Posted:
10 years ago
Attached my model if you have Comsol 5.
Attachments:
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Posted:
10 years ago
thanx a lot sir for guiding me..now i will try the way you told me