Volume Force Calculation
Use the Volume Force Calculation node if the particles exert a significant force on the surrounding fluid. This node defines dependent variables for the components of the volume force; the net volume force is equal in magnitude and opposite in direction to the total volume force on the particles.
To compute the volume force exerted by the particles on the fluid, at least one Drag Force node must be present.
The Volume Force Calculation node computes the volume force in the same way as the Fluid–Particle Interaction Multiphysics node but does not automatically include the accumulated variables as source terms when computing the fluid velocity and pressure. For modeling bidirectionally coupled fluid-particle interactions, consider using The Fluid–Particle Interaction Interface instead of the Volume Force Calculation node.
For more information about the calculation of the volume force, see Volume Force Calculation in the section Theory for the Fluid–Particle Interaction Interface.
Volume Force Calculation
This section is available if Specify release times is selected from the Particle release specification list in the physics interface Particle Release and Propagation section. Select an option from the Force multiplication factor specification list: From physics (the default) or User defined.
•
If From physics is selected and the Enable macroparticles check box is cleared in the physics interface Additional Variables section, the multiplication factor is 1.
•
If From physics is selected and the Enable macroparticles check box is selected in the physics interface Additional Variables section, the multiplication factor is based on the auxiliary dependent variable for the multiplication factor, which is typically specified in release feature settings. If the physics interface has name fpt, this variable has name fpt.nn.
•
If User defined is selected, enter a value or expression for the Force multiplication factor n (dimensionless). The default is 1.
The Force multiplication factor can be used to represent each particle as a group of n particles that follow the same trajectory. This means that the magnitude of the contribution to the volume force by each particle is multiplied by n.
If Specify mass flow rate is selected from the Particle release specification list in the physics interface Particle Release and Propagation section, the Force multiplication factor n cannot be specified because the number of particles represented by each model particle is instead controlled by the Mass flow rate, which is specified in the settings for release features such as theRelease and Inlet nodes.