Pressure
can be applied to surfaces or shell elements. When writing out to
an output file, the pressure will be applied to the shell elements
or the attached faces of the solid element, depending on what solver
is chosen and the type of pressure. The direction the pressure is
applied is based on the surface normals of the shell elements, or
is applied into the volume for volume mesh. A circle symbol will be
displayed on a surface to indicate application of pressure, as shown
in the figure below.