The normal velocity and tangential force condition combines the concepts of the normal and tangential velocity and force conditions described in Normal and Tangential Velocity Condition and Normal and Tangential Force Condition. A typical use of this condition is for the upper free surface of a basin with zero normal velocity and zero shear forces (or full slip along a wall). Another example is a moving boundary with an imposed uniform value of and, in case of slip, a zero value of . As mentioned in the previous sections, zero values for and are most common, but nonzero values are also possible (although not a nonzero value for in 3D). If the tangential force in a 3D problem is nonzero, you should use the global force condition (described in Global Force Condition) instead.

To define the normal velocity and tangential force on a boundary section, select the Normal velocity and tangential force imposed (vn, fs) menu item in the list of boundary condition choices.

  Normal velocity and tangential force imposed (vn, fs)

Then specify as a Constant, a Linear function of coordinates, a Map from CSV (Excel) file, or a User-defined function. When you select Upper level menu after specifying , Ansys Polydata will bring you to the menu where you can specify as a Constant or a Linear function of coordinates.