Fluid dynamics of phytoplankton with spines in unsteady shear flows

Spines and other thin projections from cell surfaces literally expand the volume of fluid with which a cell interacts and may provide effective levers on which the flow can act. We use an immersed boundary formulation to solve the coupled phytoplankton-fluid system to predict the 3D trajectories of the cells within a background flow. We examine the effect of spines on the trajectories, along with the effect of stiffness properties of these spines.