COLLEGE OF SCIENCES

SCHOOL OF EARTH AND ATMOSPHERIC SCIENCES

EAS Ph.D. Defense

Hamid Karani

October 27, 2017

10:00 AM

Earth and Atmospheric Sciences

Ford Environmental Science & Technology (ES&T)311 Ferst Drive, ES&TAtlanta, GA 30332-0340Web: eas.gatech.edu

ES&T

1177

Title: A Multiscale Analysis of Heat Transfer in Porous Media

Committee members: Dr. Huber, Dr. Dufek, Dr. Simon,Dr. Ferrier, Dr.Magin(External committee member from U. Illinois at Chicago)

Abstract: The modeling of thermal convection in porous media is a challenging task due to the inherent structural and thermophysicalheterogeneities that permeate over several scales. In the present thesis, we address several issues relevant to buoyancy

driven thermal convection in porous media. Our approach is based on establishing

a multi-scale framework build on knowledge accrued by theoretical, numerical and

experimental methods.

In Chapter 2, we develop a pore-scale computational tool based on a lattice Boltzmann(LB) model. This computational tool enables us to tackle thermal convection

from a pore-scale perspective and to provide benchmarks for the development of an

appropriate continuum-scale models. In Chapter 3, we use our LB model and conduct

high-resolution direct numerical simulation at the pore scale. The objective is to evaluate the underlying assumptions of upscaledthermal models and to assess the role of

thermophysicalheterogenetieson heat transfer. We benefit from the insights gained

from our pore-scale results and propose a new upscaledenergy model for thermal

convection in Chapter 4. The proposed model is based on a fractional-order advectiveterm, which models the influence of thermal heterogeneities in a flexible and

consistent way. In Chapter 5, we used a combination of theoretical and experimental

approaches to calculate a new metric, basin stability, for quantifying the respective

relative stability of coexisting convection modes in porous media. We show that transition between convective modes predicted by the basin stability analysis agrees well

with the experiments from our IR thermography visualization setup.