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Interior Normal Velocity
The Interior Normal Velocity node, found under the Interior Conditions submenu, adds the boundary condition for a moving interior boundary. This can, for example, represent a thin vibrating structure or s speaker membrane. The condition reads
The condition ensures that the total normal velocity is defined on both the up and down side of the boundary, while applying a slit on the pressure (the pressure is discontinuous across the boundary).
Normal Velocity
Select the Type: Velocity (default) or Normal velocity and specify either the Velocity (vector) v0 or the normal component through the Normal velocity vn.