Pipes, stratified, wave motion

A fundamental account of unsteady motion in a dense suspension requires knowledge of phase interactions and origins of wavy stratified motion [Zhu, 1991 Zhu et al., 1996]. Flow stratification involves a dense phase of solids flowing along the bottom of a horizontal pipe with wave motions, or a layer of the dense phase of solids flowing near the wall of a vertical pipe with wave motions. The former was analyzed, in part, on the basis of the theoretical work of de Crecy (1986) on stratified liquid-vapor flows. 

In gas-solid multiphase flows, the wave propagation method is commonly used to study the stability of stratified pipe flows, where an analogy to gas-liquid wave motion with a free surface is prominent. The perturbation method is commonly used to study the stability of a fluidized bed. In the following, both methods are introduced. 

To simplify the analysis of wave motions in stratified pipe flows, several assumptions can be made ... 

Zhu, C., Soo, S. L. and Fan, L.-S. (1996). Wave Motions in Stratified Gas-Solid Pipe Flows. Proceedings ofASME Fluids Engineering Division Summer Meeting, San Diego, California. 1, 565. ASME. 

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