couple/cfd/force command

Syntax

fix ID group-ID couple/cfd/force

  • ID, group-ID are documented in fix command

  • couple/cfd = style name of this fix command

  • zero or more keyword/value pairs may be appended

  • keyword = force or torque or transfer_superquadric or transfer_ellipsoid or transfer_stochastic or transfer_property or CAddRhoFluid

    force values = implicit or excplicit
  for allocating memory required for implicit/explicit drag force handling
    torque values = implicit or excplicit
  for allocating memory required for implicit/explicit hydrodynamic torque handling
    CAddRhoFluid value = CAdd RhoFluid
  CAdd = Coefficient for additional mass term. (Usually 0.5)
  RhoFluid = Fluid density
    transfer_superquadric values = yes or no
  for allocating memory required for handling superquadrics
    transfer_stochastic values = yes or no
  for allocating memory required for handling stochastic dispersion

Examples

fix cfd all couple/cfd couple_every 100 mpi fix cfd2 all couple/cfd/force

fix cfd all couple/cfd couple_every 100 mpi fix cfd2 all couple/cfd/force force implicit transfer_type yes

fix cfd all couple/cfd couple_every 100 mpi fix cfd2 all couple/cfd/force force implicit transfer_property name color type scalar-atom

Description

The command couple/cfd/force can only be used in combination with fix_couple_cfd. This model transfers the force that the fluid exceeds on each particle to the DEM calculation. At every coupling time step the force term, which contains contributions from all force models active in the CFD calculation, is passed on to LIGGGHTS®. This (constant) term is then used in the particle calculations at every DEM time step until the next coupling takes place. Additionally Ksl and Uf terms are transferred to LIGGGHTS® unless the force is set to explicit.

Note

It is strongly recommended to use the fix nve/cfd_cn/* integrator style with implicit force terms, otherwise these will be ignored.

Additional information, as the LIGGGHTS® atom_type can be transferred to the CFDEMcoupling environment with the keywork transfer_type yes. Similar keywords are transfer_density, transfer_torque and the more general transfer_property. The syntax is transfer_property name “name” type “data-type”. The data-type can be scalar-atom or vector-atom and this needs to be a per atom property previously defined.

The option CAddRhoFluid enables additional mass terms for the integration of particles. These model the influence of displaced fluid on the particle motion.

Restrictions

transfer_superquadric = yes requires atom_style superquadric

Related Commands: fix couple/cfd

Default

force implicit:all(b)