Embolus Transport Simulations with Fully Resolved Particle Surfaces

It is generally agreed that the transport of emboli in the large blood vessels is important in determining its fate and its risk for stroke. It is difficult, however, to calculate a trajectory of arbitrarily large particles. The commonly used “small” particle assumption, i.e. forces acting on the particle may be modeled with a drag law, is justified if the particle length scale is much smaller than the flow length scale. In this work, we simulate the motion of embolus-like particles through the blood using an overset mesh technique in conjunction with a Navier-Stokes solver for the blood flow. This allows the fluid stresses on the particle surface to be fully resolved. The particles can consequently be of arbitrary size and shape. We simulate the trajectory of 150 resolved particles through a patient-specific carotid artery bifurcation, with particles of 0.5 and 1.0 mm diameter spheres and 1.0 mm x 0.5 mm spheroids. We also simulate the trajectory of about 10000 particles using the “small” assumption. The proportions of small and non-small particles entering the internal carotid artery are treated as the outcome of the particle fate, and statistical comparisons are made to ascertain the importance of non-small particle effects.