Particles on Demand method: theoretical analysis, simplification techniques and model extensions

The Particles on Demand method [B. Dorschner, F. Bösch and I. V. Karlin, {\it Phys. Rev. Lett.} {\bf 121}, 130602 (2018)] was recently formulated with a conservative finite volume discretization and validated against challenging benchmarks. In this work, we rigorously analyze the properties of the reference frame transformation and its implications on the accuracy of the model. Based on these considerations, we propose strategies to boost the efficiency of the scheme and to reduce the computational cost. Additionally, we generalize the model such that it includes a tunable Prandlt number via quasi-equilibrium relaxation. Finally, we adapt concepts from the multi-scale semi-Lagrangian lattice Boltzmann formulation to the proposed framework, further improving the potential and the operating range of the kinetic model. Numerical simulations of high Mach compressible flows demonstrate excellent accuracy and stability of the model over a wide range of conditions.