Circulation of micro-particles in stenosed microvessels: nanoworm outperforms sphere

We explore the circulation of micro-particles (MPs) in stenosed microvessels with different constriction ratios and lengths through three-dimensional fluid-structure interaction simulations. The blood flow dynamics is solved by Lattice Boltzmann method (LBM). We employ coarse-grained model to capture the dynamics of red blood cells (RBCs) and MPs. And the LBM and coarse-grained model are coupled by immersed boundary method. We find that high constriction ratio enhances the accumulation of spherical particles in the front of the constriction, while lowers the margination of spherical particles after the constriction. This effect becomes more significant for the microvessels with longer constriction length. However, nanoworms demonstrate different distributions along the flow and in the axial directions. Comparing with spherical MPs, nanoworms distribute more uniformly without obvious accumulation in front of the constriction region along the flow. In the axial direction, nanoworms show stronger concentration in the center of the flow. It is attributed to the deformability that nanoworms can deform under the shear flow and migrate to the center of blood stream.