Updating the Loth Drag Model to Include Nonspherical Particle Effects

Abstract

Sophisticated drag models have been developed over the past few decades that are based on ballistic range and other experimental data. These drag models are applicable over a wide range of particle-flow environments and include compressibility and rarefaction effects. One drawback of these sophisticated drag models is that they assume spherical particles. However, Martian dust particles and materials used in ground-based dusty-flow experiments such as [Formula: see text] or BN are known to be nonspherical. It is well known that nonspherical particles, in general, will experience higher drag forces compared to spherical particles. There has also been a considerable amount of research developing drag models that account for nonspherical particle shapes, but most of these models are restricted to incompressible, continuum particle-flow conditions. This paper presents a simple way to include nonspherical particle effects into the widely used Loth particle drag model. This updated drag model is used to simulate dust-laden flow experiments performed in the German Aerospace Center the multiple phase flow facility (GBK) experimental facility and in the shock layer of a Martian-entry spacecraft to assess the effectiveness and range of applicability of this new drag model. In the GBK experiment simulations, the modified Loth drag model, which includes both compressibility and nonspherical particle effects, showed improved comparison to the experimental data.