Defined in couplingProperties dictionary.
momCoupleModels ( model );
- model = name of the momCoupleModel to be applied
momCoupleModels ( implicitCouple );
This examples list might not be complete - please look for other models (momCoupleModel_XY) in this documentation.
Forces can be coupled in an implicit way to the fluid solver (i.e., when solving the Navier-Stokes equations, the fluid velocity at the new time will be considered for the coupling force). This implicit coupling is typically done for the drag forces (look for “impForces()” in the implementation of the drag model). Implicit coupling is more stable (especially important for dense flows), but conflicts Newton’s third law. Explicit forces are imposed on the flow solver in an explicit fashion (look for “expForces()” in the implementation of the drag model), which is less stable, but does not conflict Newton’s third law.
Note that the switch “treatVoidCellsAsExplicitForce true;” can be set in the couplingProperties in order to change the treatment of cells which are void of particles. This is only relevant if (i) smoothing is used, and (ii) implicit force coupling is performed. By default, the particle veloctiy field (Us) will be smoothed to obtain a meaningful reference quantity for the implicit force coupling. In case “treatVoidCellsAsExplicitForce true;” is set, however, Us will not be smoothed and implicit forces (after the smoothing has been performed) in cells void of particles be treated as explicit ones. This avoids the problem of defining Us in cells that are void of particles, but for which an implicit coupling force is obtained in the smoothing process.
The momCoupleModel is the base class for momentum exchange between DEM and CFD simulation.