Main Help → All Commands → MPM Analysis Header → FeedbackDamping
The FeedbackDamping
command adds viscous grid damping to particle velocities during MPM calculations:
FeedbackDamping (gain),<(Tk)>,<(maxAlpha)>
where (gain)
is a feedback gain term that determines the evolution of the particle damping coefficient (the feedback calculation). The damping coefficient has units of 1/(length units)2. The default is 0 or no damping. The optional parameter (Tk)
is a user-defined function of time that evaluates to a target kinetic energy in alt energy units. The default value is 0.
The optional parameter (maxAlpha)
can specify a maximum grid damping coefficient (αg) entered in units of 1/time units (same units and similar effects as the grid damping coefficient). The default is to have no limit to damping, but a maximum can be used to prevent out-of-control overdamping. When a limit is needed, however, it might be a symptom of a poor simulation with too much kinetic energy.
You can refer to the OSUPDocs wiki for information on grid, particle, and PIC damping, and information on how feeadback damping evolves with kinetic energy in the simulation, and how to chose target kinetic energy is some problems.
FeedbackDamping
command is only allowed for MPM analyses.