The Prescribed Velocity node adds a boundary or domain condition where the velocity is prescribed in one or more directions. The prescribed velocity condition is applicable for Time Dependent and Frequency Domain studies. It is possible to prescribe a velocity in one direction, leaving the solid free in the other directions. The
Prescribed Velocity node is a constraint and overrides any other constraint on the same selection. The
Prescribed Velocity node is only available with some COMSOL products (see
https://www.comsol.com/products/specifications/).
Select one or all of the Prescribed in x direction,
Prescribed in y direction, and
Prescribed in z direction check boxes (only applicable check boxes are shown based on the spatial dimension). Then enter a value or expression for
vx,
vy, and
vz. For axisymmetric components, select one or both of the
Prescribed in r direction and
Prescribed in z direction check boxes. Then enter a value or expression for
vr and
vz. When twist is included in 2D axisymmetry, the circumferential displacement can also be prescribed.
In a stationary study, this node can either be ignored or treated as a constraint (similar to a Prescribed Displacement node with zero displacement). To control this, select an option from the
Displacement in stationary study list —
Free or
Constrained.
