Saurabh S. Sawant

University of Illinois, Urbana-Champaign | UIUC · Department of Aerospace Engineering

An efficient, new DSMC framework based on AMR/octree unstructured grids is demonstrated for the modeling of near-continuum, strong shocks in hypersonic flows. The code is able to capture the different length scales in such flows through the use of a linearized representation of the unstructured grid using Morton-Z space filling curve for efficient...

A multi-scale modeling approach based on the stochastic Direct Simulation Monte Carlo (DSMC) and walker methods is developed to understand the complex flows and thermophysical phenomena through a syntactic foam TPS, similar to AVCOAT. Using novel, unstructured adaptive mesh refinement/Octree grids and newly developed subsonic boundary conditions, t...

Low-frequency molecular fluctuations in the translational nonequilibrium zone of one-dimensional strong shock waves are characterised for the first time in a kinetic collisional framework in the Mach number range $2\le M\le 10$. Our analysis draws upon the well-known bimodal nature of the probability density function (PDF) of gas particles in the s...

Linear global instability of the three-dimensional (3-D), spanwise-homogeneous laminar separation bubble (LSB) induced by shock-wave/boundary-layer interaction (SBLI) in a Mach 7 flow of nitrogen over a $30^{\circ}-55^{\circ}$ double wedge is studied. At these conditions corresponding to a freestream unit Reynolds number, $Re_1=5.2\times 10^{4}$ m$...

Linear instability of high-speed boundary layers is routinely examined assuming quiescent edge conditions, without reference to the internal structure of shocks or to instabilities potentially generated in them. Our recent work has shown that the kinetically modeled internal nonequilibrium zone of straight shocks away from solid boundaries exhibits...

View Video Presentation: https://doi.org/10.2514/6.2022-4029.vid The effect of an isolated cylindrical roughness element embedded in a laminar boundary layer on a semi-infinite flat plate in rarefied Mach~6 flow is studied using the Direct Simulation Monte Carlo method. Steady state solutions are computed only in the three-dimensional configuration...

Linear three-dimensional instability is studied in the shock layer and the laminar separation bubble (LSB) induced by shock-wave/boundary-layer interactions in a Mach 7 flow of nitrogen over a double wedge with a $30^{\circ }\text {--}55^{\circ }$ cross-sectional profile. At a free-stream unit Reynolds number $Re=5.2\times 10^{4}\,{\rm m}^{-1}$ thi...

Linear stability analysis is performed using a combination of two-dimensional direct simulation Monte Carlo (DSMC) (Bird in Molecular gas dynamics and the direct simulation of gas flows, Oxford University Press, Oxford, 1994) method for the computation of the basic state and solution of the pertinent eigenvalue problem, as applied to the canonical...

Modeling and characterization of electromagnetic wave interactions with microelectronic devices to derive network parameters has been a widely used practice in the electronic industry. However, as these devices become increasingly miniaturized with finer-scale geometric features, computational tools must make use of manycore/GPU architectures to ef...

Low-frequency molecular fluctuations in the translational nonequilibrium zone of one-dimensional strong shock waves are characterized for the first time in a kinetic collisional framework in the Mach number range 2≤M≤10. Our analysis draws upon the well-known bimodal nature of the probability density function (PDF) of gas particles in the shock, as...

Linear stability analysis is performed using a combination of two-dimensional Direct Simulation Monte Carlo (DSMC) method for the computation of the basic state and solution of the pertinent eigenvalue problem, as applied to the canonical boundary layer on a semi-infinite flat plate. Three different gases are monitored, namely nitrogen, argon and a...

Although particle-laden electrostatic discharges are widely used in research as well as in industrial applications, the mechanisms of particle lifting for a particle initially at rest in such highly unsteady flows are not well understood. A multiphase plasma flow is modeled by solving the continuum conservation equations and particles as discrete e...

During the past years joint efforts have been exerted by different researchers for the development of high speed air vehicles as well as hypersonic systems in general, for a wide range of applications. However, such systems involve rarefied gas flows, which appear to be significantly different comparing to flows at the continuum regime; it is this...

The self-excited spanwise homogeneous perturbations arising in shock-wave/boundary-layer interaction (SWBLI) system formed in a hypersonic flow of molecular nitrogen over a double wedge are investigated using the kinetic Direct Simulation Monte Carlo (DSMC) method. The flow has transitional Knudsen and unit Reynolds numbers of 3.4 x 10$^{-3}$ and 5...

Linear instability of high-speed boundary layers is routinely examined assuming quiescent edge conditions, without reference to the internal structure of shocks or to instabilities potentially generated in them. Our recent work has shown that the kinetically modeled internal nonequilibrium zone of straight shocks away from solid boundaries exhibits...

Particle-laden electrostatic discharges are widely used in research as well as in industrial applications. The mechanism of particle lifting in these highly unsteady flows are not well understood. Modifications are made to the FLASH research code to simulate this multiphase system using the Lagrangian-Eulerian (LE) approach. Various Lagrangian subm...

Pyrolysis of a phenolic polymer is a well-known heat removal mechanism in charring ablators, but the process has not been well-quantified. Here, we perform scale-bridging molecular dynamics (MD) simulations based on a reactive-force-field (ReaxFF) potential to elucidate the pyrolysis kinetics of a highly crosslinked phenolic formaldehyde resin. We...