Comparison of pressure-based and density-based solvers for scramjet modeling

High costs, as well as long set up time for the experimental investigation of scramjet combustor, has led to extensive use of numerical investigations for the design and development of the scramjet combustor. In computational fluid dynamics (CFD), the velocity-pressure-density coupling algorithms can be classified into two distinct families, namely pressure-based and density-based methods. Traditionally, pressure-based solvers were developed for low-speed incompressible flow regime, while density-based solvers were developed for high speed compressible flow regime. However, over the years these methods have been enhanced to simulate both the flow regimes. The supersonic flow in the combustion chamber of a scramjet is commonly studied using a density-based solver as it is considered to offer better shock resolution capabilities as compared to a pressure-based solver. However, currently, pressure-based solvers are also capable of modeling high speed compressible flow regime. In this work, the performance of these two solvers as implemented in ANSYS FLUENT is investigated by simulating experimental scramjet configuration. Cold flow simulations are investigated with appropriate boundary conditions. Results of both the solvers are compared with the experimental data. It is observed that both the pressure based solver and density based solver results are in good agreement with the experimental data. However, in terms of convergence speed the pressure based solver shows distinct advantage.