Welcome to the website of Multiphysics Flow Simulation Group (MFSG) at The University of Alabama in Huntsville (UAH). We have a research interest in a number of areas where multiple physical or chemical phenomena involving a fluid or plasma interact with each other.

Turbulent structure of a shrub fire plume obtained by physics-based modeling (Padhi et al., FSJ, 2017) and displayed by isosurfaces of the second invariant of the velocity gradient with a magnitude of 15s-2

Physics based modeling of wildland and wildland-urban interface (WUI) fires has been a significant part of our research efforts for the past several years. Wildland and WUI fires are multiphysics phenomena where many physical and chemical processes such as combustion, gravity driven flows, turbulence, solid fuel pyrolysis, thermal radiation and convective heating simultaneously interact with each other over a broad range of scales. Through physics-based modeling, we find solutions for mathematical (differential) equations that represent these coupled processes and hence describe the fire behavior. Since there is a wide range of time and three dimensional spatial scales in wildland and WUI fires, we conduct massive computations through parallel processing to resolve the scales with a sufficient accuracy.

Two examples of grain charge vs dimensionless time, characterized by metastability (Shotorban, PRE, 2015).

Another major activity in our group concerns dusty plasmas (a.k.a. complex plasmas), which contain nano- to micro-meter size solid particles in addition to ions and electrons. Dusty plasmas are found in space and processing industry where plasmas are used. A dust grain collects ions and electrons from the plasma and gains a net electric charge that randomly fluctuates over time.

A project in our group has been on description of this type of fluctuation, which is an intrinsic noise inherent in the actual mechanism responsible for the evolution of the system and cannot be switched off. We recently showed through stochastic modeling that the charge fluctuations may become metastable when the effects of the secondary electron emission from the grains are included. Metastability of fluctuations is manifested by the passage of the grain charge between two macrostates.