Increasing the efficiency and maneuverability of one-hinge swimmer

Abstract

Understanding the dynamics of micro-organisms will help in developing artificial swimmers for applications like drug delivery. In the present study, a two-dimensional one-hinge swimmer resembling a scallop in Newtonian fluid is explored. To model the one-hinge swimmer, we use bead-spring model and the fluid is simulated using multi-particle collision dynamics with Anderson thermostat. We consider a non-uniform distribution of the bending rigidity along the arms of the swimmer, where we reduce the bending rigidity progressively from the hinge to the end of the arms. The non-uniform arms show higher swimming speed for the same average bending rigidity, thereby enhancing the efficiency of the swimmer. It was observed that the bending rigidity variation along the arm of the swimmer following a geometric sequence was more efficient than linear or quadratic for the same average bending rigidity. We also study the maneuverability of the one-hinge swimmer having asymmetrical bending rigidity for the arms, thereby the swimmer undergoes curved path. We find that depending upon the stiffness of the arm, the swimmer undergoes clockwise or anticlockwise rotation. We also find that the angular and transnational velocities of the swimmer are maximum at approximately the same sperm number ∼1.8. The angular velocity of the swimmer scaled linearly with the amplitude of actuation as predicted by resistive force theory. Finally, we show that in the case of a two-dimensional one-hinge swimmer angular velocity, curvature and the direction of rotation can be controlled by just changing the relative bending rigidity of the arms.