### Computational Models of Self-Propelled Microorganisms

Ricardo Cortez

School of Science and Engineering

Tulane University

Many microscopic biological phenomena involve thin filaments interacting with a fluid. Some examples are the motion of bacteria swimming by the actuation of flagella, the coordinated motion of cilia, the swimming of spermatozoa, and artificial self-propelled microswimmers. The interaction of thin filaments with nearby surfaces or moving through regions in the fluid containing elastic polymers are also of interest since these environments are commonly found in nature. I will describe the method of regularized Stokeslets, which was developed as a computational tool to model microscopic bodies interacting with a viscous fluid. The method is based on fundamental solutions of linear partial differential equations modified in such a way that the singularities are eliminated. A recent variation of the method, the regularized Stokeslet segments, designed for thin filaments will also be described. I will show results from simulations of flagellar motions with asymmetric beat patterns and the effect of swimming near a solid surface. Recent work on models of swimming through viscoelastic regions incorporate the effect of the elastic polymers immersed in the fluid using a network of crossâlinked nodes where each link is modeled by a simple viscoelastic element. I will show results from preliminary studies that aim to determine how swimming performance is affected by the properties of the viscoelastic network.