6 papers
Noise-separated evidence for a slow collective displacement in a rarefied hypersonic bow-shock layer
Ahmad Shoja-sani, Ehsan Roohi
Time-resolved direct simulation Monte Carlo (DSMC) fields are used to test whether a detached rarefied hypersonic bow shock contains a slow collective displacement that can be sepa…
Rarefaction-induced inflation and similarity breakdown of hypersonic bow shocks over a circular cylinder
Ehsan Roohi, Ahmad Shoja-Sani
Rarefied hypersonic bow shocks over blunt bodies inflate as the Knudsen number increases, but it remains unclear whether this inflation is a simple shift and broadening of one comm…
Physics Constrained Neural Collision Operators for Variable Hard Sphere Surrogates and Ab Initio Angle Prediction in Direct Simulation Monte Carlo
Ehsan Roohi, Ahmad Shoja-Sani, Stefan Stefanov
The Direct Simulation Monte Carlo (DSMC) method is the gold standard for non-equilibrium rarefied gas dynamics, yet its computational cost can be prohibitive, especially for near-c…
Learning Rarefied Gas Dynamics with Physics-Enforced Neural Networks
Ehsan Roohi, Ahmad Shoja-Sani, Bijan Goshayeshi +1
This study develops and validates neural network frameworks with physics-based constraints for surrogate modeling of rarefied gas dynamics across different levels of complexity. As…
Data-Driven Surrogate Modeling of DSMC Solutions Using Deep Neural Networks
Ehsan Roohi, Ahmad Shoja-sani
This study presents a deep neural network (DNN) framework that accelerates Direct Simulation Monte Carlo (DSMC) computations for rarefied-gas flows, while maintaining high physical…
Efficient Collision Algorithms in DSMC for Rarefied Gas Dynamics: Markovian NTC-Pre-Scan and Bernoulli-Trial Schemes
Ahmad Shoja-sani, Maryam Javani, Ehsan Roohi +1
The collision process is essential to the Direct Simulation Monte Carlo (DSMC) method, as it incorporates the fundamental principles of the Boltzmann and Kac stochastic equations.…