model Type A or B and Coupling Interval

Submitted by rfbrpr on Sat, 09/01/2012 - 16:33

Dear All:

I have been finding in the CFDEM manual the meaning of the above terms but with no succes. Could you explain what they mean?

Regards

Rafael

Forums:

cgoniva's picture

cgoniva | Tue, 09/04/2012 - 13:14

Dear Rafael,

>> model type: refers to the formulation of the equations to be solved, please find details here:

+ in "couplingProperties" the model type must be specified, see Zhou et al. (2010): "Discrete particle simulation of particle-fluid flow: model formulations and their appliccability", JFM

Please note, that depending on the model type you need to apply the Archimedes lift force, gradP, viscForce. The Program will tell you if something is missing.

>> couplingInterval:

set the DEM TS in the in.xxx according to the needs of the pure DEM problem,

then set the coupling interval in couplingProperties as "couplingInterval" which refers to the DEM timesteps. Depending on the problem you will need to have a close (small couplingInterval) / loose coupling.
(e.g. if DEMts=0.00001s and couplingInterval=10 it will exchange data (=couple) every 0.0001s)

now choose the CFD timestep in the controlDict. it must be equal or smaller than the coupling time, otherwise you will get the error: "Error - TS bigger than coupling interval!".

Hope that helps you further?

Cheers,
Chris

jorisheyman | Thu, 11/22/2012 - 15:18

Is that possible to choose an adjustableTimeSTep for CFD calculus, so that CFL condition does not exceed 1, but still having coupling every dt seconds ?

cgoniva's picture

cgoniva | Tue, 12/04/2012 - 16:09

Hi,

I usually do not use this adjustableTimeSTep setting -
it might work to use it - but at least slight errors will occur -> so I will not recommend to use it.

Some deep thougts and some coding might be needed to generalize the coupling routine to allow for adjustableTimeSTep.

Cheers,
Chris