enable_fem_coupling command

Purpose

Coupling between Elmers Elasticsolver for meshes and Aspherix®

Syntax

enable_fem_coupling id ID coupling_timestep ct keyword value

• id = mandatory keyword

• ID = name of command

• coupling_timestep = mandatory keyword

• ct = coupling time step size [time]

• zero or more keyword/value pairs may be appended

• keyword = fem_timestep or coupling_timeout

coupling_timestep value = coupling_ts
  coupling_ts = time step size of data exchange between DEM and FEM
fem_timestep value = fem_ts
  fem_ts = time step size of FEM (default: coupling_timestep)
coupling_timeout value = ct
  ct = maximum duration allowed while waiting during coupling

Examples

enable_fem_coupling id fem coupling_timestep 1e-3
enable_fem_coupling id fem coupling_timestep 1e-3 fem_timestep 1e-4 coupling_timeout 100

Description

This command allows the coupling of a DEM simulation with an FEM simulation. It will automatically launch an instance of Elmer with the same number of processors as Aspherix®. Additionally, this command can be specified in the mesh command so that boundary meshes from elmer will be imported as boundary mesh to Aspherix®.

For a detailed example please see the tutorial on FEM coupling.

The keyword coupling_timestep determines the time spent in the DEM simulation between the exchange of the forces and displacements with the FEM simulation. If the fem_timestep is not set explicitly, the coupling_timestep will als be used as the time integration step size of the Elmer simulation. Please note that the ratio of the coupling_timestep and the DEM time step, as set by the simulation_timestep, must be an integer value. If this is not the case, an error will be shown and the simulation will be terminated.

Finally, the coupling_timeout determines how long the two simulators wait for each other while performing their work. Especially on slower systems it might be required to increase this value to prevent unexpected termination of a simulation.

Additional information

This command stores the node deformation (total and step) as additional mesh properties, which can be output via the output_settings command. Please see the documentation of that command for more details on how to output mesh properties in general.

Defaults

fem_timestep = coupling_timestep, coupling_timeout = 10