Using low Reynolds number sediimentating and rotating spheroids to calibrate numerical models

Biological experiments and numerical simulations are the most common methods of studying the swimming of microorganisms. However, biological measurements used to calibrate numerical simulations generally have large uncertainties. The Trinity-Centre Collaboration uses dynamically similar, macroscopic low Reynolds Number experiments to precisely calibrate the method of regularized Stokeslets and the method of images for regularized Stokeslets (MIRS) to extract quantitatively accurate values for the forces and torques on a bacterial model moving near a boundary. We previously produced calibration data and optimal computational parameters for cylinders, helices (Shindell et al., Fluids, 2021) and spheres (Nguyen et al, Phys. Rev. Fluids, 2025). Our latest experiments measure the forces and torques acting upon a spheroid sedimenting near a boundary. We measured 3D position, roll, pitch, and yaw using stereo video to track surface features on a 3D-printed spheroid. We have so far recreated 2 of the 4 trajectory types characterized in Mitchell and Spagnolie (J. Fluid. Mech. 2015) for several prolate spheroids. Future work will include oblate spheroids and torque on spheroids as a function of boundary distance. We will use this data to find the optimal computational parameters for the MIRS and compare them to the results for spheres.