## General

#### What is the meaning of the coordinates delivered by the ‘center of pressure’ postprocessing functionality within FLUENT?

• FAQ
Participant

Letâ€™s look at a flat plate exposed to constant pressure. For this plate the centre of pressure will have the same position as the center of gravity. The pressure force vector will be oriented in surface normal direction and act on the center of gravity. If the plate is supported at the center of gravity, it will stay in equilibrium with zero turning moment. In FLUENT after choosing the wall zones to evaluate the center of pressure from, the user has to provide an arbitrary x or y or z coordinate as an additional input. In exchange FLUENT does calculate the remaining 2 coordinates for the center of pressure. So instead of a unique centre of pressure, there are multiple solutions. What is the meaning of these â€˜off (plate) surfaceâ€™ points calculated in FLUENT by choosing one coordinate value? In the case of the flat plate example, all possible points do lie on the pressure force vector passing through the center of gravity. So in 3D the center of pressure for an arbitrary surface/structure is located on unique straight line defined by the pressure force vector passing through the â€˜originalâ€™ center of pressure. (With that approach one also gets into trouble, if the pressure force vector does not intersect with the x/y/z-plane prescribed as a user input.) All this is quite easy to prove for e.g. one face of a cube.