Unsteady effects on the flow across tilting disk valves

Area of Science:

• Computational Fluid Dynamics (CFD)
• Biomedical Engineering
• Cardiovascular Mechanics

Background:

• Mechanical heart valves are critical medical devices requiring precise design.
• Understanding fluid dynamics around these valves is essential for performance and safety.
• The role of unsteady flow effects in the fully open position needs clarification.

Purpose of the Study:

• To numerically simulate and analyze the flow across 2D tilting disk mechanical heart valve models.
• To evaluate the significance of unsteady flow effects versus steady conditions.
• To compare simulations with fixed versus moving valve models under physiological flow.

Main Methods:

• Time-dependent Navier-Stokes equations were solved numerically.
• Simulations included steady and physiological inflow conditions.
• Analyses were performed for both fixed and moving valve configurations.

Main Results:

• Steady inflow simulations neglecting vortex shedding do not accurately represent physiological flow.
• While gross flow features are similar, detailed flow fields can differ between fixed and moving valves.
• Fixed valve simulations provide reliable estimations of critical parameters like axial force and shear stress.

Conclusions:

• Fixed mechanical heart valve simulations are adequate for estimating critical design parameters in the fully open state.
• Physiological inflow conditions are necessary for realistic flow modeling.
• Fixed valve simulations offer a practical approach for prosthetic heart valve design, focusing on the fully open position.