Varad Abhimanyu Karkhanis
I work as Systems Engineer in SP Scientific, a division of SP Industries based in Gardiner, NY. Some of the interesting works that I do at SP includes modelling Lyophilization processes, and numerical simulations of compressible water-vapor flow in vacuum for commercial lyophilizers.
I graduated with my Ph.D. degree in Mechanical Engineering in July 2017 from University of North Carolina at Charlotte. My Ph.D. dissertation work involved fully compressible, multiphase, shock-driven ‘Richtmyer-Meshkov' instability in metal-vacuum configuration to study flow of molten metals in vacuum under extreme conditions. This problem is of direct relevance to experiments performed at Los Alamos National Laboratory, and one of the significance of this work is- comparison of simulation results with experiments.
Recently, I have taken up an adjunct faculty position in SUNY New Paltz. I teach 'EEG331: Computer Simulation' for undergraduate students. Some of my research interests include Computational Fluid Dynamics (CFD), Lyophilization process modelling, turbulence modelling, and thermal & heat transfer analysis for variety of engineering problems.
MY LATEST RESEARCH
Continuum Simulations of Ejecta production from second shock
From detailed numerical simulations and comparison with recent experiments, we explore ejecta production at an interface that is impulsively accelerated by two successive shock waves. The perturbed material interface demarcates the boundary between a metal and vacuum resulting in the formation of ejecta driven by the Richtmyer-Meshkov instability. The numerical simulations were performed with the astrophysical FLASH code, in which the shocked metallic response is conceptually modeled using continuum hydrodynamics. The experimental data were obtained from a two-shockwave, high-explosive tool at Los Alamos National Laboratory capable of generating ejecta from a shocked Sn surface in to a vacuum.
Scrambled and Unscrambled Turbulence
The linked fluid dynamics video depicts Rayleigh-Taylor turbulence when driven by a complex acceleration profile involving two stages of acceleration interspersed with a stage of stabilizing deceleration. Rayleigh-Taylor (RT) instability occurs at the interface separating two fluids of different densities, when the lighter fluid is accelerated in to the heavier fluid. The turbulent mixing arising from the development of the miscible RT instability is of key importance in the design of Inertial Confinement Fusion capsules, and to the understanding of astrophysical events, such as Type Ia supernovae. By driving this flow with an accel-decel-accel profile, we have investigated how structures in RT turbulence are affected by a sudden change in the direction of the acceleration first from destabilizing acceleration to deceleration, and followed by a restoration of the unstable acceleration. By studying turbulence under such highly non-equilibrium conditions, we hope to develop an understanding of the response and recovery of self-similar turbulence to sudden changes in the driving acceleration.