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Alternate tangential impact treatments for the soft-sphere collision model

Abstract The linear-slider-dashpot (LSD) soft sphere model is used extensively to model particle collisions in dense particle systems. The contact mechanics in the normal and tangential directions are modeled by a spring, damper, and dashpot system. The current work evaluates different existing tangential direction implementations of the LSD model. The existing models require storing the cumulative tangential displacement for each collision pair. The article evaluates existing tangential models and develops alternative methods which do not require storing the tangential deformation. The models are tested for two canonical single particle experiments of oblique impacts and sphere traveling on a surface. It is shown that some of the existing implementations fail to validate with at least one of the test cases. In one proposed model, Model-C, the tangential displacement is approximated as the product of the characteristic time of collision with the instantaneous particle tangential contact velocity. In a second proposed model, Model-D, the instantaneous non-dimensional impact angle is used to characterize the impact according to Maw et al.’s analysis. Both models give reasonably good predictions in the two test cases with the quality of predictions as good or better than some existing implementations which require the storage of the tangential deformation.