ISSN:
1089-7666
Source:
AIP Digital Archive
Topics:
Physics
Notes:
This study investigates the stability of a laminar, cocurrent flow of a concentrated suspension below a clear fluid layer in a plane, horizontal channel. The suspension is treated as a Newtonian fluid with effective density and viscosity dependent on the particle concentration. In such cases, the flow problem resembles the stratified flow of two different superposed fluids, which is well known to be unstable to long interfacial waves. The evolution equation for long interfacial waves is derived by employing a method of multiple time scales and a regular perturbation technique. In this study, the particle concentration within the suspension layer is a function of the local height of the perturbed interface. A wall slip boundary condition for the suspension is employed at the bottom wall of the channel. The evolution equation is Burgers' equation, which predicts the behavior of an initial disturbance. The variable particle concentration affects the stability of the flow. For a small ratio of clear fluid to suspension layer thickness, an unstable region exists if the Froude number is below a critical value. Favorable density stratification stabilizes the flow. Finally, it is shown that interfacial waves modify the pressure loss in the channel, which is in agreement with an earlier experimental observation. © 1998 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.869797
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