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72 lines
2.4 KiB
Plaintext
72 lines
2.4 KiB
Plaintext
"CFDEMproject Website"_lws - "Main Page"_main :c
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:link(lws,http://www.cfdem.com)
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:link(main,CFDEMcoupling_Manual.html)
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:line
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momCoupleModel command :h3
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[Syntax:]
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Defined in "couplingProperties"_CFDEMcoupling_dicts.html#couplingProperties
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dictionary.
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momCoupleModels
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(
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model
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); :pre
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model = name of the momCoupleModel to be applied :ul
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[Examples:]
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momCoupleModels
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(
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implicitCouple
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); :pre
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NOTE: This examples list might not be complete - please look for other models
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(momCoupleModel XY) in this documentation.
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[Description:]
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Forces can be coupled in an implicit way to the fluid solver (i.e., when solving
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the Navier-Stokes equations, the fluid velocity at the new time will be
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considered for the coupling force). This implicit coupling is typically done for
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the drag forces (look for "impForces()" in the implementation of the drag model).
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Implicit coupling is more stable (especially important for dense flows), but
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conflicts Newton's third law. Explicit forces are imposed on the flow solver in
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an explicit fashion (look for "expForces()" in the implementation of the drag
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model), which is less stable, but does not conflict Newton's third law.
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Note that the variable {imExSplitFactor} can be set in the couplingProperties in
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order to treat implicitly defined forces (in the implementation of the force
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model) as explicit ones. {imExSplitFactor 1.0;} is set by default, meaning that
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all implicit forces will be considered implicitly, whereas
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{imExSplitFactor 0.0;} would mean that implicitly defined forces will be treated
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in an explicit fashion.
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Note that the switch {treatVoidCellsAsExplicitForce true;} can be set in the
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couplingProperties in order to change the treatment of cells which are void of
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particles. This is only relevant if (i) smoothing is used, and (ii) implicit
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force coupling is performed. By default, the particle velocity field (Us) will
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be smoothed to obtain a meaningful reference quantity for the implicit force
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coupling. In case {treatVoidCellsAsExplicitForce true;} is set, however, Us will
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not be smoothed and implicit forces (after the smoothing has been performed) in
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cells void of particles be treated as explicit ones. This avoids the problem of
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defining Us in cells that are void of particles, but for which an implicit
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coupling force is obtained in the smoothing process.
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The {momCoupleModel} is the base class for momentum exchange between DEM and CFD
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simulation.
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[Restrictions:]
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none
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[Default:]
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none
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