Improving Heat Flux Predictions in Multi-Wall Hypersonic Flows Using a Low Dissipation Sensor

Numerical solvers are essential tools for simulating atmospheric entry environments. The Kentucky Aerodynamic and Thermal-response System Fluid Dynamics (KATS-FD) solver is designed to model hypersonic flow environments. The original use of the Steger-Warming flux scheme to handle inviscid flux vectors introduced excessive numerical dissipation, notably in flows involving converging-diverging nozzles. In particular, its directional dissipation mechanism led to inaccuracies in wall-parallel flow solutions and cases involving multiple walls. To address this, a low dissipation version of the Ducros sensor was implemented within the KATS-FD Steger-Warming scheme. This allows for dissipation only to be added in regions where either a shock or stagnation region is present. Unlike alternative approaches such as the AUSM scheme, the improved sensor operates without requiring reference values, allowing for solutions to be generated with less specific inlet conditions. This study examines the behavior of several dissipation strategies, comparing their respective advantages and limitations. Surface heat-flux distributions are also evaluated on a test case to quantify the performance of each sensor and to assess their suitability for hypersonic flow simulations.