RAYLEIGH -TAYLOR INSTABILITY IN STRONG MEDIA

S. M. Bakhrakh, N. P. Kovalev
VANT. Ser.: Mat. Mod. Fiz. Proc. 1995. Вып.1-2. С. 33-37.

      The analytical study results are presented for Rayleigh-Taylor instability in elastic and viscous media. These results are suggested for testing numerical methods. Two applications are emphasized. The evolution of sinusoidal perturbations of the interface between an elastic medium and perfect gas under the constant acceleration g directed towards solid body. In this case (unlike the gases) there exists a critical perturbation wavelength λ _k. The exponential, amplitude growth occurs only for the perturbations with the wavelength λ > λ _k.
      For the pulse acceleration the interface fluctuates with the period defined as the shear module and density function. A useful test is the evolution of the perturbed interface between viscous fluid and a gas under pulse acceleration. In this case, as opposed to inviscid gases, the exponential factor appears decreasing the amplitude growth rate. This solution is interesting in that it can be used for the evaluation of approximation viscosity in numerical methods for gas-dynamic (inviscid) flows.