AC7-03

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Abstract

Heart failure is a cardiovascular disease, which affects millions of people worldwide. If the heart failure is to severe, a heart transplantation is the gold standard for treatment. Unfortunately, a significant shortage of donor hearts exists worldwide. A technical solution to overcome this gap between demand and availability are Ventricular Assist Devices (VADs). The VADs are mainly implanted within the body of the patients and assist the weak heart by creating the needed pressure to sufficiently supply the blood flow in the circulatory system.

The devices must be designed in such a way that the operating range maintain the blood flow. For this purpose, a defined pressure head $H$ must be built up at a certain blood flow rate $Q$. Whether a VAD design meets these fluid mechanical requirements can be checked by flow simulations in the pre-clinical evaluation. Furthermore, a VAD must be designed for highest hemocompatibility, which means that the blood components in the flow are not damaged due to non-physiological flow condition. This can be checked by analysing the fluid dynamical stresses $\tau$ by flow simulations and combine them with a numerical blood damage prediction model (these are called the hemodynamical parameters).

In this context, the present ERCOFTAC KB Wiki entry examine the turbulent flow field in a VAD, which is computed by flow simulations. A highly flow-resolving large-eddy simulation (LES) is compared as a reference with a unsteady Reynolds-averaged Navier-Stokes simulation (URANS) with a $k$-$\omega$-SST turbulence model (standard procedure in industry for flow simulation in VADs) with respect to the computed fluid mechanical and hemodynamical parameters. In particular, the question is to what extent URANS can reproduce the fluid mechanical parameters (head, efficiency) and to which extend are the shear stresses and blood damage prediction results comparable to the reference LES. Furthermore, two verficiation methods are appliedm by which an adequate shear stress computation for the URANS and LES can be evaluated (numerical error consideration). In particular, the grid dependences of the flow quantities of interest are discussed.

THe shown results are part of different publications by the author. More information on the topic can be found in ...

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Contributed by: Benjamin Torner — University of Rostock, Germany

Front Page

Description

Test Data

CFD Simulations

Evaluation

Best Practice Advice

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