Gravity waves at the interface between miscible fluids and at the top of a settling suspension.

Gravity waves were generated at the interface between miscible fluids, or at the top of a settling suspension or a fluidized bed. For these three systems the dispersion relation was measured and compared to the theory and calculated between two buoyant viscous fluids without surface tension. The experimental findings are found to be in good agreement with theory when effective viscosity and volume-averaged density values are used.