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-   -   divergence issue when updating dpm sources (https://www.cfd-online.com/Forums/fluent-multiphase/229623-divergence-issue-when-updating-dpm-sources.html)

mohamadalimirzaei1994 August 17, 2020 13:53

divergence issue when updating dpm sources
 
I have two similar cases using k-omega SST turbulence model and DDPM multiphase model:

case 1. dpm iteration interval is greater than max iteration per time step, so the DPM source is not updated within each time step (urf DPM =1)

case 2. dpm iteration interval is set 2 and the reporting interval is 4 so at least 2 dpm source update occurs for each time step (urf DPM 0.9)

the first case is fine and does not have any divergence issue, but the second one divergence after a while (with turbulent viscosity ratio warning)

in both cases, I track overall DPM sources and there in no sharp change from one iteration to another and from one time step to another.

as I understood, to ensure that DPM sources are calculated accurately at least on update must occur in each time step so that is why I moved from case 1 to case 2.

what can be the cause of such divergence?


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