Topology optimization method applied to the design of rotor and volute of ventricular assist devices based on the viscosity effect (Tesla principle)

Abstract

This work is part of the thematic project "Sistemas propulsores eletromagnéticos para coração artificial implantável e dispositivos de suporte circulatório mecânico" ("Electromagnetic propelling systems for implantable artificial heart and mechanical circulatory support devices"), FAPESP number 2013/24434-0. This work is inserted in the research line of Ventricular Assist Devices (VADs), aiming the optimization of the rotor and volute of small scale flow pumps based on the viscosity effect (Tesla pumps). Since VADs are used to temporarily substitute or assist the heart of a patient, the increase in its efficiency in energetic terms and the reduction of hemolysis is of great interest. The increase of its efficiency can be achieved by optimization methods, such as the topology optimization method, which is able to create the shapes of the rotor and the volute. The modelling will be of a non-Newtonian fluid (blood). The optimization problem is structured with a multi-objective function, aiming to indirectly minimize the head loss caused by the energy dissipation (in order to reduce the hemolysis rate), minimize the actuator torque, minimize the vorticity (in order to reduce the blood coagulation) and maximize the hydraulic head of the flow. The material model to be used in the topology optimization is based on the "density method". The implementation will be done in the FEniCS platform, using the adjoint method for calculating the derivatives (dolfin-adjoint) and interior point optimization algorithm (IPOPT). The topology optimization results will be interpreted and fabricated by using additive manufacturing (i.e., 3D printer), being characterized in terms of flow rate and hydraulic head generated by the prototypes. (AU)