An Assessment of the Particle Modeling Fidelity for Particle-Induced Transition Simulations

Particles are present in the atmosphere as well as in wind tunnels and can have a significant effect on the characteristics of high-speed boundary layer flows. Particles can introduce small-scale disturbances inside the boundary layer, which are subsequently converted into wavepackets that can get amplified while they travel downstream. The strong amplification of these wavepackets inside the boundary layer can transition the flow to turbulence. Modeling these transition mechanisms can be challenging due to the need of accurately capturing particle-flow interactions. These interactions are simulated by employing two different simulation approaches: 1) a particle-source-in-cell method considering a quasi-steady drag-force-based particle model and 2) fully resolving the particle by employing a higher-order immersed boundary method. Before evaluating the accuracy of the particle-source-in-cell method for particle-induced transition simulations, the correct implementation is verified. A detailed grid sensitivity study is performed to select an appropriate grid resolution and simulation setup for the IBM and PSIC simulations. The particle-flow interactions are simulated for a Mach 5.35 boundary layer flow considering different particle sizes and impingement locations and the numerical results are compared between the two simulation approaches. Overall, it was found that the PISC method underpredicts the disturbance amplitudes introduced by particle impingement in comparison to high-fidelity fully-resolved simulations.