University of Minnesota
Aerospace Engineering and Mechanics
Fall 1997 Seminar Series



Simulation of Particulate Flows of Newtonian and Viscoelastic Fluids


Professor Howard H. Hu
Department of Mechanical Engineering and Applied Mechanics
University of Pennsylvania


Abstract


A numerical method for computing motions of large numbers of particles (particle mover) in flows of solid-liquid mixtures was developed. In the method the fully coupled motions of liquid and solid are solved using a finite element technique, and solid particles move under the action of the hydrodynamic forces and moments exerted by the suspending fluid. The developed package is able to simulate the motion of particles in both Newtonian fluids, governed by the Navier-Stokes equations, and in several popular models of non-Newtonian viscoelastic fluids. Using this package, we have studied the motion of large number solid particles in Newtonian and Oldroyd-B fluid subjected to a pressure gradient. The particles can be neutrally or non-neutrally buoyant. We used a ratio of the applied pressure gradient and the pressure gradient at fluidization to identify various flow regimes: lubricated flow with assisting pressure gradient, mixed flow before fluidization, mixed flow after fluidization and lubricated flow with opposing pressure gradient. Effects of various flow parameters on these flow regimes will be presented. We also investigated the effect of inertia (finite particle Reynolds number) on the macroscopic properties of a suspension of rigid particles in a Newtonian and an Oldroyd-B fluid. The particle-fluid mixture was subjected to uniform shear flow between two parallel plates. We observed that a Newtonian suspension shear thickens while a suspension in Oldroyd-B fluid shear thins. The first normal stress difference at finite Reynolds number for a Newtonian suspension is negative (pulling the shearing plates together) while that for a suspension in Oldroyd-B fluid was positive (pushing the shearing plates apart).


Friday, November 14, 1997
209 Akerman Hall
2:30-3:30 p.m.


Refreshments served after the seminar in 227 Akerman Hall.
Disability accomodations provided upon request.
Contact Audrey Stark-Evers, Senior Secretary, 625-8000.