| The primary focus of this work is to investigate unsteady flow simulations for an incompressible fluid. Computational codes are developed and applied for the purpose of analyzing the flow in a centrifugal heart pump, the Innovative Ventricular Assist System (IVAS) pump, which was developed by the Cleveland Clinic Foundation as a part of the National Institute of Health's artificial heart program. In order to simulate the complex flow in the IVAS pump, three capabilities must be incorporated into the simulation codes. The first capability is that the code must be able to simulate the flow through an IVAS pump for Reynolds numbers {dollar}30,000{lcub}sim{rcub}80,000{dollar} with numerical stability. The Reynolds numbers in this range are considered to be high in incompressible flow and to have difficulty in simulating a flow with numerical stability. The second capability is that the codes must solve 2-1/2 dimensional Navier-Stokes equations. The 2-1/2 dimensional Navier-Stokes equations are written in such a way that the effect of the variable thickness is included in two-dimensions. The 2-1/2 dimensional analysis enables the simulation of the flow, including the various thickness effects, at nearly the computational speed of two-dimensional analysis. The third capability is that the code must simulate the flow for the entire centrifugal pump, which includes an inlet, rotating blades, a volute, and a diffuser. To perform this intensive calculation, parallel computing is used because of its high computing speed and its ability to accommodate the large computational domain by task partitioning. An intensive parametric study using a single-processor computer is performed with a view to identifying certain problematic aspects of the design methodology. According to the present analysis, the effects of a Reynolds number based on the blade radius and its velocity are not significant for typical pump operation conditions. The flow characteristics, however, change with the Reynolds numbers when they are low. In general, the pressure rise across the pump impeller increases as the radius of the blade arc increases and as the number of blades increases. The findings of this study qualitatively agree with the Euler turbine equation with respect to the effects of the leading edge (inflow) angle and the trailing edge (outflow) angle. |
