The basic idea behind this is Archimedes' principle, which says this is equal to the weight of the displaced fluid.
The Boussinesq approximation is used in flows driven by this. In one formulation, this force is equal to the pressure at the lower point of contact times the area at that point minus the pressure higher point times that point's area. This is proportional to both gravitational acceleration and the density of the fluid. The basic idea behind this is Archimedes' principle, which says this is equal to the weight of the displaced fluid. For 10 points, name this force that allows objects to float in water.
The Boussinesq approximation is used in flows driven by this.
{buoyancy} [accept {buoyant force}]