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-   -   Help: CURRENT_TIMESTEP with FLUENT Steady Solver (https://www.cfd-online.com/Forums/fluent-udf/114452-help-current_timestep-fluent-steady-solver.html)

lihuang March 11, 2013 11:37

Help: CURRENT_TIMESTEP with FLUENT Steady Solver
 
Dear all,

I am trying to model partitioning of organic compounds between gas and granular phases. I use DEFINE_SOURCE macro to pass mass transfer rate back to steady solver. As I understand that time dependent terms are not included in the equations solved by fluent steady solver. But when it comes to calculating mass transfer in DEFINE_SOURCE macro, I have delta_t involved. And CURRENT_TIMESTEP macro does return a constant value of 1, which seems a fake time step. It seems to me now that the mass transfer rate defined in DEFINE_SOURCE should not involve delta_t. Please correct me if i am wrong.

Thanks.

msaeedsadeghi March 13, 2013 02:57

You're right.

lihuang March 14, 2013 10:25

Quote:

Originally Posted by msaeedsadeghi (Post 413584)
You're right.

Hi Saeed,

Thanks so much for your clarification.

For Fluent Steady Coupled solver, there is a Courant number, which can be set to change local time step for solving continuity and momentum equations according to fluent 6.x user's guide. The default value for steady coupled implicit Courant number has been changed from 5 (fluent 6.x) to 200 (fluent 12.1). And in fluent 12.1, Courant number for pressure-based coupled solver of value lower than 10 is NOT recommended by the guide. So I am wondering if there are some sort of changes have been made.
Could anyone please comment on this?

Thank you all!

Li


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