# University of Minnesota

Aerospace Engineering and Mechanics

**Fall 1997 Seminar Series**

*Simulation of Particulate Flows of Newtonian and Viscoelastic
Fluids*

*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.