Comparison between RayleighTaylor instabilities of compressible and incompressible fluid

Comparison between RayleighTaylor instability growth rates of compressible and incompressible fluid is made, with the state equation of compressible fluid in an arbitrary function form of density and pressure. It is shown that with the same density distribution, interface perturbation growth rate of compressible fluid is always greater than the counter one. The relative growth rate increases with perturbation wavelength, and decreases with velocity of sound of upper and lower fluid. The value of relative growth rate can exceed 0.8 at long wave and more compressible fluid, so compressibility of fluid shouldn't be neglected at some conditions.