Dynamic similarity requires that the ratio of all forces be the
same. The ratio of different forces produces many of the key
non-dimensional parameters.These include Reynolds number that is
ratio of inertia force to viscous force.Froude number that is ratio
of inertia force to gravitional force,weber number ratio of inertia
force to surface tension,Roosby number inertia force to coriolis
force and mach number inertia force to compressibillity force.These
can be derived by non-dimensionalising the differential equation of
fluid flow.
There are many non dimensional groups in heat and mass transfer
as well.
