Velocity of small particles in a compressible fluid

The density and viscosity of a compressible fluid increases as pressure increases but tends to leave off at high pressure. We have significant compression or expansion on a gas so that thermodynamic states temperature, internal energy, entropy can change. Smaller particles have a larger surface area to mass ratio so there settling rates are slowed more by frictional dragging than are larger particle. The applications of studies would be helpful in designing mixing devices, designing of particle separator devices and the prediction of the settling of pollutant particles, seeds and pollen.