CFDEM simulation using two dimension scales - SI and MICRON

Submitted by AndresMM on Wed, 11/22/2017 - 13:40

Hi Everybody,

I am doing a CFDEM simulation of a microfluidic chip. On the OpenFOAM you have to use SI units. On the LIGGGHTS side you have choices. Since my microfluidic chip requires very small particles, I am working with micron units in the LIGGGHTs script.

Am I right believing the CFDEM-coupling assumes that we are working with SI units at all times? Checking the results in paraview it is obvious there is a big incongruence in the results from CFD and DEM. I imagine this arises from the code just tracking numbers and not the units, which he assumes to be SI.

How can this problem be solved? Unfortunately, the small particle size together with the small insert region on the LIGGGHTS-side is causing problems when using SI-units

Cheers,
-A

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AndresMM | Thu, 11/23/2017 - 14:23

Hi everyone, setting both to cgs units allows to have both simulations talk to each other was they should.

I have however one question regarding the application used when edoing CGS-based CFDEM-coupling. In the controlDict from ErgunTestMPI_cgs the application is pisoFoam and not cfdemSolverPiso, why is this?

alice's picture

alice | Mon, 11/27/2017 - 10:40

Hi Andreas,
the application setting in the controlDict is not used by any part of our rountine (the solver for the Allrun.sh is set within the parCFDEMrun.sh file) and the setting doesn't really matter. It should be cfdemSolverPiso in both cases.
Cheers,
Alice