Zoom link https://kaust.zoom.us/j/96269043941

Committee members

• Prof. Deanna Lacoste – Ph.D. Advisor
• Prof. Cafer Yavuz – Committee Chair
• Prof. Ashwin N. Chinnayya – External examiner
• Prof. Peter J. Schmid – Committee member from ME program)

Abstract

Gaseous detonations are fundamental to the design and safety of advanced propulsion systems and industrial processes. However, a persistent gap exists between the outcomes of numerical simulations and the results of physical experiments, limiting the predictive accuracy. This thesis advances the predictive simulation of gaseous detonations in hydrogen–oxygen mixtures with inert dilution (argon and nitrogen) by systematically addressing the current discrepancies between numerical predictions and experimental measurements. The work begins with the verification, validation and an update of an OpenFOAM^®-based detonation solver, reactingPimpleCentralFoam capable of running 1D, 2D and 3D detonation simulations in both lab- and shock-frame of references, with the current state-of-the-art methodologies in the literature. While fundamental detonation features are captured, discrepancies arise in predicted detonation cell widths when compared with experimental data.

To understand these discrepancies, a detailed evaluation of chemical kinetic models is performed. For the first time, numerical predictions of induction zone length (Δ_i) variation are directly compared with high-resolution NO- and OH-PLIF based diagnostics. Diffusion effects are shown to play only a minor role in shaping detonation cellular structures for H₂-air mixture at low pressures. Building on these insights, the thesis quantifies the role of reaction rate uncertainty by systematically perturbing key reactions across multiple mechanisms. This analysis demonstrates that modest variations in most sensitive reaction rates (within  uncertainty) can produce significant changes in predicted cell size, Δ_i dynamics directly linking kinetic uncertainty to the numerical–experimental gap. A modified kinetic model is identified that brings simulations into closer agreement with experimental cell size and Δ_i, although certain dynamic features remain imperfectly captured. By addressing kinetic uncertainty, this work reduces part of the gap and provides clear direction for the next steps. Ongoing three-dimensional with adaptive mesh refinement aim to capture the geometric complexity of detonation fronts, while future work will incorporate vibrational non-equilibrium to further improve predictive fidelity. 

Bio

Vigneshwaran Sankar received his Bachelor’s degree in Aeronautical Engineering from Kumaraguru College of Technology, India in 2017, and his Master’s degree in Aerospace Engineering (Propulsion and Combustion) from the Indian Institute of Technology Kanpur, India in 2020. He is currently a Ph.D. candidate in Mechanical Engineering in the Physical Science and Engineering Division at King Abdullah University of Science and Technology (KAUST), Saudi Arabia. His research focuses on multidimensional hydrogen detonation simulations with detailed chemistry using OpenFOAM.