How can I get Eulerian Multiphase model converged?

Hi, I am doing Euler-Euler multiphase simulation with two secondary (solid) phase and one primary (gas) phase. This is my model set up:

Vertical Domain (reactor) : 0.038 * 0.45 m

sand (1st solid phase) dim: 0.00024 mm

coal (2st solid phase) dim : 0.00024 mm

mesh size= 0.0024 mm

sand volume fraction: 0.59

coal volume fraction: 0.3 (to have a certain mass of coal by having its density and volume)

First I patched the sand inside the reactor with a defined volume fraction and temperature and gas entered the reactor from bottom and then the model got converged . Then I increased the number of Eulerian phase from 2 to 3 and defined the coal material and its phase interactions along with its volume fraction and temperature inside the reactor domain. But when I am going to define this new solid phase (coal), fluent shows me the following error:

Error: GENERAL-CAR-CDR: invalid argument [1]: improper list

and also the simulation gets diverged, showing floating point exception error.

I tried to handle this issue by changing Under relaxation factors but it still gets diverged. It would be very helpful if anyone could give a few advice on this.


Best regards

Answers

  • kkourbatkkourbat Forum Coordinator

    you should be starting the run with all the phases defined, and not incrementally increasing their number. For phases which do not exist initially, simply set their fraction to zero, and then increase this value to a required number once the initial run is converged

  • Once I did like you said but since the volume fraction of 2th solid phase was defined zero, its velocity increased largely around 10^4 m/s.

  • This (Error: GENERAL-CAR-CDR: invalid argument [1]: improper list) was due to increasing phase number before defining new material and now its resolved.

    But there are still following messages and then divergence:

    Reverse flow in some faces of pressure outlet

    Stabilizing temp to enhance linear solver

    Temperature limited to ....

    Thanks for your time!

  • RobRob UKForum Coordinator

    It's probably transient and check when you patch in the second granular phase that the overall mass fraction doesn't exceed the packing limit. If that does happen the particles must separate to reflect the limit and will do so very quickly.

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