Unsteady effects on the flow across tilting disk valves.
The present study simulates numerically the flow across two-dimensional tilting disk models of mechanical heart valves. The time-dependent Navier-Stokes equations are solved to assess the importance of unsteady effects in the fully open position of the valve. Flow cases with steady or physiological inflow conditions and with fixed or moving valves are solved. The simulations lead into mixed conclusions. It is obvious that steady inflow cases that account for vortex shedding only cannot model realistic physiological cases. In cases with imposed physiological inflow, the details of the flow field for fixed and moving valves might differ in the fully open position as well, although the gross features are quite similar. The fixed valve case consistently results in safe estimations of several critical quantities such as the axial force, the maximal shear stress on the valve, or the transvalvular pressure drop. Thus, fixed valve simulations can provide useful information for the design of prosthetic heart valves, as long as the properties in the fully open position only are sought.
Rosenfeld
Moshe
M
Faculty of Engineering, Tel Aviv University, Israel. rosenf@eng.tau.ac.il
Avrahami
Idit
I
Einav
Shmuel
S
D001696:Biomechanical Phenomena; D001783:Blood Flow Velocity; D020342:Finite Element Analysis; D006350:Heart Valve Prosthesis; D006801:Humans; D008943:Mitral Valve / Q000502:physiology*; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011673:Pulsatile Flow; D012039:Regional Blood Flow / Q000502:physiology*; D015203:Reproducibility of Results; D012212:Rheology; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013997:Time Factors