Flow field evolution in a laboratory model of the left ventricle

An experimental apparatus simulating the velocity field downstream of an artificial heart valve in a model of the left ventricle was developed. In particular, the cardiac cycle was reproduced by a linear motor such that both healthy and unhealthy conditions could be reproduced. In this study, a one-way, hydraulic valve has been inserted in a mitralic orifice and a strong, uniform-velocity jet which enters the ventricle is generated. This condition is very similar to the inflow generated by the natural valve. To measure the velocity field the working fluid was seeded with tracer particles and the test section, the middle plane of the ventricle model, was lit by a laser light sheet. A long time image sequence of the flow field was acquired by a high-speed camera. The Feature Tracking image analysis technique was used to quantify particle displacements and as a result a Lagrangian description of the fluid trajectories were obtained. The evolution of particle trajectories and the velocity fields during the whole cardiac cycle is presented here. The Eulerian velocity field were also evaluated to characterize the flow. Finally, the viscous shear stresses were analyzed, in order to compute the quantities that are considered to be the main cause of the blood cells damage.