I work on heat and mass transfer in reacting systems.  My research interests cover combustion, heat transfer, and aerosols.  I am particularly interested in applied thermal engineering and have ongoing research in jet flames, fire dynamics, polymer thermal decomposition, and IC Engines.  Here is some of our recent work in applied CFD.

Research Projects:

Fire Dynamics

We have conducted large scale (house scale) tests of Positive Pressure Ventilation (PPV) in collaboration with the Austin Fire Department.  We continue to investigate the dynamics of human (firefighter) to fire coupling.  The fire and firefighter influence each other, and we are trying to better understand the science of this coupling.  We use experiments and computations to better understand how specific firefighting tactics can be best implemented. We are creating a fire education web site.  Here is a recent presentation of how an Authority Having Jurisdiction (AHJ) might use Fire Dynamics Simulator (FDS).

Jet Flames

Jet Flames: In this study we computationally simulate the fluid mechanics and combustion dynamics associated with laminar and turbulent jet flames. We are attempting to create simple engineering design tools and guidelines from detailed experiments and calculations. We have developed an acoustically coupled burner system where we can control the luminosity (amount of soot) and length of the flame.

Aerosol Evolution

We have investigated several different aspects of aerosol evolution.  This spans characterizing the production of combustion generated aerosols (e.g., soot) to evaluation of various aerosol remediation strategies.  Mathematical descriptions of aerosol evolution are computationally difficult to solve because the equations are often integro-differential equations. We use moment formulations of the underlying pdfs and moment closure methods to develop computationally efficient tools for aerosol analysis. Examples of our work in the aerosols area are available.

Predicting the thermal degradation rates of thermoplastics is critical for modelling plastic ignition and flame spread for fire applications and the recession rate in thermochemical ablation.  Traditionally, models developed for polymer thermal degradation are essentially curve fits to thermogravimetric analysis (TGA) data.  For a given set of fitting parameters, it is possible to adequately model the TGA data at the specified conditions. In general, however, when these fit kinetics are used to extrapolate to other conditions (e.g., higher heating rates) they are are much less accurate.  A self-consistent description of the thermal degradation of thermoplastics  is possible using the radical depolymerization kinetic concept. The mathematical description of the polymer is population balance based, where the internal variable is a size parameter (e.g., polymer molecular weight).    The resulting evolution equation for the size parameter density function (akin to a pdf) is an integro-differential equation that can be solved using sectional methods, moment methods, etc.  Like our aerosol work, we use moment formulations and moment closure approximations to more fundamentally define model parameters to describe the polymer degradation processes.

NIST (Dept. of Commerce), AFOSR, NASA (micro-gravity), NSF (CAREER), GCHSRC, 3M Corp, Ford Motor Company, ARL-UT , Department of Energy, Texas Utilities Electric Corp., Texas Higher education Coordinating Board