Added mass fluid quasi-momentum. Unsteady forces due to a change of the relative velocity of a body submerged in a fluid can be divided into two parts: the virtual mass effect and the Basset force. The origin of the force is that the fluid will gain kinetic energy at the expense of the work done by an accelerating submerged body. It can be shown that the virtual mass force, for a spherical particle submerged in an inviscid, incompressible fluid is where bold symbols denote vectors, formula_2 is the fluid flow velocity, formula_3 is the spherical particle velocity, formula_4 is the mass density
Chirp mass terms of other common mass parameters: where formula_7 is the total mass of the system, formula_8 is the reduced mass of the system, formula_9 is the mass ratio, and formula_10 is the symmetric mass ratio. In general relativity, the phase evolution of a binary orbit can be computed using a post-Newtonian expansion, a perturbative expansion in powers of the orbital velocity formula_11. The first order gravitational wave frequency, formula_12, evolution is described by the differential equation where formula_14 and formula_15 are the speed of light and Newton's gravitational constant, respectively. Integrating equation () with respect to time gives: where C