Key result
An unstructured moving grid finite volume method applied to a tilting disk heart valve demonstrated significant differences between steady and unsteady flow solutions.
Why the study?
Numeric simulation of unsteady flows in mechanical heart valves with moving leaflets and multiple passages presents major computational challenges due to grid generation and moving boundaries.
Steady-state models may underestimate tilting-disk valve flow dynamics; leaves open whether unsteady simulations improve device design or outcomes.
The time varying flow pattern in the vicinity of mechanical heart valves (MHV) is fairly complex: it involves multiple passages and moving leaflets. The numeric simulation of unsteady flows in these multiple passages with moving boundaries presents a major challenge to computational fluid dynamics (CFD). Two major difficulties in the numeric simulation of MHV flows are 1) the generation of a body fitted grid within the multipassage device and 2) moving leaflets. The conventional finite difference and finite volume scheme obtained by using a structured grid have serious deficiencies in these applications. To fit the grid lines with the various angles of the moving MHV, the grid may often become too skewed for accurate numeric solution. To overcome these deficiencies, significant effort and attention should be placed on the grid generation and moving grid scheme. We present an unstructured moving grid finite volume method for heart valve simulations. The Navier-Stokes equations are discretized on a general tetrahedral mesh by using a finite volume scheme. With this scheme, the mesh can be automatically generated with any commercial software. The method is applied to a tilting disk (Medtronic Hall 29mm, Medtronic, Inc., Minneapolis, MN) heart valve, and results are compared with that of the steady flow solutions. Significant differences between steady and unsteady flow solutions are observed.
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Hsu et al. (1999) studied Mechanical heart valves. Unstructured moving grid finite volume method vs. Steady flow solutions was evaluated on Flow solutions. An unstructured moving grid finite volume method applied to a tilting disk heart valve demonstrated significant differences between steady and unsteady flow solutions.
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