Mach wave and acoustical wave structure in nonequilibrium gas-particle flows

In this Element, the gas-particle flow problem is formulated with momentum and thermal slip that introduces two relaxation times.

Starting from acoustical propagation in a medium in equilibrium, the relaxation-wave equation in airfoil coordinates is derived though a Galilean transformation for uniform flow.

Steady planar small perturbation supersonic flow is studied in detail according to Whitham's higher-order waves.

The signals owing to wall boundary conditions are damped along the frozen-Mach wave, and are both damped and diffusive along an effective-intermediate Mach wave and diffusive along the equilibrium Mach wave where the bulk of the disturbance propagates.

The surface pressure coefficient is obtained exactly for small-disturbance theory, but it is considerably simplified for the small particle-to-gas mass loading approximation, equivalent to a simple-wave approximation.

Other relaxation-wave problems are discussed. Martian dust-storm properties in terms of gas-particle flow parameters are estimated.