Low Reynolds number robotic swimmers utilizing surface traveling waves

El Departamento de Ingeniería Civil Mecánica de la Universidad de Chile tiene el agrado de invitarlos al seminario “Low Reynolds number robotic swimmers utilizing surface traveling waves” dictado por el Prof. Shimon Haber, de la Facultad de Ingeniería Mecánica del Tecnion- Israel Institute of Technology. A realizarse el martes 3 de Abril a las 14:30 hrs en la Sala de Seminarios en el cuarto piso de la torre central.

Micro-scale slender swimmers are frequently encountered in nature and recently in micro-robotic applications. The swimming mechanism examined in this talk is based on small transverse axisymmetric travelling wave deformations of a cylindrical long shell. The shell is assumed to be of finite wall thickness and extensible at the surface wetted by the fluid.
Experiments were conducted, using a macro-scale autonomous model immersed in highly viscous silicone fluid. We outline how the proposed mechanism was realized to propel an elongated swimmer. Measured data demonstrate the effects of the wave velocity and wavelength on the swimming speed, fitting qualitatively to our analytical results.
Assuming low Reynolds number hydrodynamics, an analytical solution is derived for waves of amplitudes small compared with the cylinder diameter. It is shown that the swimming velocity increases with b₁, the ratio between the cylinder radius and the wavelength, that the swimming velocity is linearly dependent on the wave propagation velocity, increases to leading order with the square of the ratio between the wave amplitude and the wavelength, b₂, and decreases with the wall thickness.
The present mechanism was also compared with Taylor’s well known solution of a waving circular tail. We show that the present approach yields higher velocities as b₁ increases, while the opposite occurs to a waving tail. Indeed, in the region where b₁>15 the present approach yields velocities nearly as fast as Taylor’s helical waving tail, with a considerably more compact design, and twice the velocity of Taylor’s planar-tail swimmer for an additional investment of only one third of the power.