An immersed boundary method for particle-resolved simulations of arbitrary-shaped rigid particles

The present work extends the direct-forcing immersed boundary method introduced by (García-Villalba et al., 2023), broadening its application from spherical to arbitrarily-shaped particles, while maintaining its capacity to address both neutrally-buoyant and light objects (down to a density ratio of 0.5). The proposed method offers a significant advantage over existing methods regarding its simplicity, in particular for the case of neutrally-buoyant particles. Three test cases from the literature are selected for validation: a neutrally-buoyant prolate spheroid in a shear flow; a settling oblate spheroid; and, finally, a rising oblate spheroid. • Immersed boundary method extended to handle neutrally-buoyant and moderately-light bodies. • Quaternion-based forumlation for the treatment of non-spherical objects. • The final expressions are simple, especially for the case with neutrally-buoyant bodies. • Spectral/spectral-element simulations of settling and rising spheroids used for validation.