Use the Prescribed Normal Mesh Velocity node to specify the normal velocity of the boundary. The node can be used on the boundary of domains with free displacement. No constraints are set on the tangential velocity.
where v0 is the desired normal mesh velocity, and
vmbs is a smoothing velocity according to:
Here δmbs is a moving boundary smoothing tuning parameter (unitless),
h is the mesh element size (SI unit: m), and
H the mean surface curvature (SI unit: 1/m), defined as:
where ∇T is the surface gradient operator.
By default, the Enable moving boundary smoothing check box is not selected. To enable boundary smoothing, click to select the check box, and then enter a value or expression for the
Moving boundary smoothing tuning parameter,
δmbs (unitless). The default value is 0.5.
As the local mesh element size h at a boundary is included in the expression for
vmbs, a large value for
δmbs can result in an uneven velocity of mesh movement along a boundary. For this reason, it is recommended to use the smallest
δmbs needed to achieve a stable solution.