Multiphase Multispecies

  • Last Post 12 June 2020
krndv posted this 29 May 2020


I am a solving a multiphase multi-species problem with phase 1 has 4 species and phase 2 has 2 species. The species balance is defined by source terms and no reaction is defined. 

One of the species in phase 2 is dependent on the concentration of a species in phase 1.

Please help me with how to extract a mass fraction of components from each phase specifically.

I have read the UDF manual but getting regular error. Used THREAD_SUB_THREADS(t); macro for defining it.



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rwoolhou posted this 03 June 2020

What error are you getting? We don't support UDFs, but you should be able to pick up the species concentration on the phase. 

krndv posted this 08 June 2020

It diverges in the first iteration.


rwoolhou posted this 09 June 2020

So, something in the set up means something is changing far too rapidly for the solver to be stable.  Is the model transient?

krndv posted this 11 June 2020

Yes the model is transient.



rwoolhou posted this 11 June 2020

Try initialising to all one phase and use a smaller time step. If you remove the UDF does it work?

krndv posted this 12 June 2020

Yes it works without udf.


rwoolhou posted this 12 June 2020

OK, so look at the UDF and remove/reduce the effect. Chances are you're changing something too quickly for the model to be stable.