f := gp.mass.gravity(gp)

Get the gravitational mass. This is determined by the density and volume of the zones to which the gridpoint is connected. The gravitational mass is used to determine forces due to gravity. In dynamic mode, it is used in the equations of motion calculation. See also gp.mass.inertial.

Returns:f - the gridpoint gravitational mass
Accepts:f - the gridpoint gravitational mass
Arguments:gp - a zone gridpoint pointer