Dear Expert,

I am solving the 2D TFM case when I use the viscous stress model (Lun et al) in TFM, simulation is running but when I change the viscous stress model (Algebraic formulation), the following error occurs:

" Invoking BC_JJ_PS required GRANULAR_ENERGY = .TRUE.

Fetal error is required on one or more processes. The .Log file may contain additional information about the failure.

please find the bug report.

gao8sc125_2024-03-16T094459.274721.zip (57.3 MB)

Dear @jeff.dietiker

Could you suggest me what i am doing wrong.

I haven’t looked at your file, but the message says you can’t use Johnson-Jackson BC unless you also turn on the granular energy equation. So you have to choose between:

Turning Johnson-Jackson BC on and solving the granular energy equation (say use the Lun et. al viscous stress model)

or

Turning Johnson-Jackson BC off and not solving the granular energy equation (use algebraic formulation for the viscous stress model)

Dear Jeff,

you said for solving the granular energy (KTGF) always on Lun et al viscous stress model, whether using

Johnson-Jackson BC or not. am I writing?

if I use algebraic formulation for the viscous stress model it will not solve KTGF but the simulation is working so what will affect the simulation results ?

If you want to solve for granular temperature you have to use one of the kinetic theory viscous stress model (i.e. not the algebraic model). Lun et al. is one of them. Then you can use JJ BC or not.

The algebraic formulation computes the granular temperature locally, there is no transport equation for it. It is a simpler (and more stable) formulation. You will get results with the algebraic formulation and with the transport equation. It is up to you to decide if the results are good enough for your simulation objective.