Wall
The Wall subnode defines the surface properties of the radiating object. That is, how the surface sources are defined. Several Wall subfeatures can be added to represent different properties of the boundaries of the surface. Note that the term “wall” here is very generic as it can also represent, for example, an acoustic source boundary. Select the Type as Velocity (the default), Normal velocity, or User defined.
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For Velocity, enter the components of the vibrating surface velocity v. This could be the velocity that results from modeling a vibrating surface like the hull of a ship or and engine. For example, if the vibrating object is modeled by a Solid Mechanics interface, then enter the velocities as solid.u_tX, solid.u_tY, and solid.u_tZ, respectively.
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For Normal velocity, enter the normal velocity vn (SI unit: m/s). This is the normal velocity pointing into the infinite fluid domain. This can be a constant, an expression that depends on space coordinates, or it can be taken from the solution of another model.
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For User defined, enter the pressure p (SI unit: Pa) and t the normal velocity vn (SI unit: m/s) defined at the given boundary. This option gives full user control of the input to the Kirchhoff–Helmholtz integral that is set up by the Exterior Field Calculation feature.