An unstructured solver for simulations of deformable particles in flows at arbitrary Reynolds numbers

As a step in the development of a numerical procedure able to perform parallel computations of the dynamics of capsules/cells in non-physiological configurations, a numerical method is developed and its validation is described. The fluid-structure interaction problem is solved using an immersed boundary method, adapted to an unstructured finite-volume flow solver thanks to the reproducing kernel particle method. A specific treatment to ensure volume conservation of the fluid enclosed in the immersed structure is also detailed. The present paper focuses on quantitative validation of the method in 2-D, against existing reference 2-D results. Excellent agreement is obtained for configurations of capsules and vesicles evolving with or without mean flow. Applications of the method to non-zero-Reynolds-number cases, including non-trivial geometry, is shown. This unstructured immersed boundary method proves robust to tackle the dynamics of deformable particles in complex flows.