A two-dimensional potential model with vorticity release is developed in order to investigate the self propelled swimming of undulating bodies. The body is free to move not only in the forward and lateral directions, but it can also rotate around its center of mass, according to the forces and moments induced by the flow field generated by its own prescribed undulation. The numerical model is based on an unsteady potential panel code for deformable bodies. The vortex shedding process is modeled by an unsteady Kutta condition. The model is able to predict the full kinematics of the undulating foil by expressing forces and moments in terms of hydrodynamic impulse. To study a body in self-propulsion immersed in an otherwise quiescent fluid, a complete body-fluid system has to be taken into consideration with a particular attention to the exchange of internal forces. The intention is to use the simplified model for an ambitious objective: clarify the role of the added mass and of the vorticity release in the free swimming either for the initial starting accelerations and for the velocity to be reached at steady conditions.
Today a huge interest is devoted to developing autonomous vehicles with self propulsion ability. This concept involves designing fish robots in order to investigate autonomous motion capabilities, schooling effects, group motion and so on. Undulatory propulsion may result in a more effective mechanism than propeller propulsion. These subjects are not yet fully understood and a large amount of efforts are displayed both by experimentalists, biologist or computational scientists. The definition of an appropriate cost-efficiency indicator is still an open issue.
A detailed numerical study through a simplified model will allow for enhancing the most significative features and for shedding light on the relevant effects of self propelled motion. In perspective the research will be extended to the development of a robot model of a self propelling fish.