Event Detail

Event Type: 
Applied Mathematics and Computation Seminar
Friday, April 19, 2013 - 05:00
GLK 104

Speaker Info

OSU Mechanical Engineering

Despite immediate relevance to both natural and engineered systems such as
groundwater networks and chemical reactors, flows through packed beds of spheres
are not generally well understood. This is particularly true at moderate to high
Reynolds numbers where fluid inertia results in complex, three dimensional flow
features including jets and vortices. Such porescale features can have implications
for macroscale properties of engineering interest including pressure drop, dispersion,
and reaction rates.

In this work, direct numerical simulation (DNS) was used to investigate the porescale
structure of flow through synthetic sphere packings at moderate Reynolds numbers,
between 10 an 600. To first choose and validate appropriate computational models
for this problem, the relative performance of two numerical approaches involving body
conforming and non-conforming grids was examined in detail. Next, data from
simulations in the steady and unsteady inertial flow regimes was used to analyze the
characteristics of porescale vortical structures. Even at similar Reynolds numbers,
the structure and behavior of vortices observed in arranged and random packings
are remarkably different. Finally, a numerical tool was developed to study packed
bed flows using the recently developed theory of Lagrangian Coherent Structures
(LCS). LCS are invariant barriers to transport and define dynamically distinct regions
of time dependent flows. The computations were embedded directly in the DNS
solver, allowing LCS theory to be applied to complex three dimensional problems,
including packed beds, for the first time.