Modeling and simulations of the motion of bio-inspired micro swimming robots

Micro swimming robots that mimic the motion of micro organisms can carry out a variety of medical tasks including drug delivery, micro surgery and minimally invasive diagnostic tasks. Micro organisms such as spermatozoa and bacteria use their flagella to propel themselves. The artificial micro swimmer presented in this study is composed of a body that carries a medical payload, and one wave propagating tail attached to it. In this study, forces and torques exerted on the tail structure by the surrounding fluid are computed with the help of corresponding force coefficients. Rigid body dynamics computations are carried out by four-dimensional quaternion configuration to eliminate numerical error accumulation during matrix integrations, and, hence, instantaneous rotation matrix for rigid body rotation is extracted from the quaternion. Propulsive force obtained by waving tail is balanced by the drag force on the micro swimmers' total wet surface and dynamic behavior of the micro swimmer is obtained as a rigid body motion. The effect of swimmer and waving geometry is parameterized to study the swimming behavior. Simulations carried out to explore the effect of wave length, wave amplitude, driving frequency. Translational and rotational velocities and hydrodynamic power requirements are presented for each individual set of design parameters. Validity of the model is tested by comparing the numerical results and finite element simulation results. Lastly, the model is modified to utilize the mobility matrix coefficients obtained from inertia eliminated finite element simulations governed by time dependent Navier-Stokes equations.