Large-Eddy Simulation of Turbulence in Cardiovascular Flows

Abstract

A 4th-order accurate, low dissipative flow solver is used to perform Large-Eddy Simulations of three typical hemodynamic situations: the flow through the idealized medical device proposed by the American Food and Drug Administration; the intracardiac flow within an actual human left heart whose morphology and deformations are deduced from medical imaging; the flow downstream of an artificial aortic valve which arises from the blood-leaflets interaction problem. In all the cases, the subgrid scale model designed to handle wall-bounded transitional flows is successfully used and the numerical simulations compare favourably with the experimental data available. These results illustrate the potential of the Large-Eddy Simulation methodology to properly handle blood flows. They also support the idea that turbulence, even if not fully developed, may be present in cardiovascular flows, including under non pathological conditions.

Modern discontinuous Galerkin methods for the simulation of transitional and turbulent flows in biomedical engineering: A comprehensive LES study of the FDA benchmark nozzle model

“…In previous studies using the large-eddy simulation approach, a Reynolds number of Re th = 5000 has been simulated in [7] where comparably large inaccuracies have been observed as compared to experimental results which are ascribed to an insufficient mesh resolution. Good agreement with experimental results is achieved in [12], but results are only shown for a single spatial resolution. Numerical results obtained for several spatial resolutions are shown in Figure 10 for the present discretization approach.…”

“…None of these works explicitly shows results of a grid refinement study even though the authors of [7] mention that a grid independence study has been carried out for the transitional case. Parabolic velocity profiles are prescribed at the inflow boundary in [7,8,10], while turbulent fluctuations are added to the laminar profile in [12]. Although excellent agreement with experimental results is reported in previous LES studies, the reliability of the results appears to be unclear due to the limited amount of data provided by these LES studies.…”

“…Furthermore, it is mentioned that the use of linear instead of quadratic shape functions resulted in a jet breakdown at a z-location significantly larger than in the experiments. In [12], excellent agreement with measurements is obtained by prescribing turbulent fluctuations at the inflow boundary but the robustness of this turbulence injection approach is not demonstrated in that work for the transitional case. In contrast, grid-converged results are reported (but not explicitly demonstrated) in [7] without adding fluctuations to the inflow profile.…”

Speech can produce jet-like transport relevant to asymptomatic spreading of virus

“…These are large eddy simulations (46), which are well suited to study transport in turbulent flows, in particular in the context of speech production (35). In addition, they are well adapted to intermittent/transitional regimes (41,42). The spatially filtered, incompressible forms of the Navier-Stokes equations are solved.…”

The effect of turbulence on transitional flow in theFDA's benchmark nozzle model using large‐eddy simulation

“…It is important that CFD simulations are able to accurately predict not only mean quantities, but also instantaneous quantities such as turbulence, which are critical for predicting biological responses including hemolysis and thrombosis [11][12][13][14][15] and, more recently, have been used to improve understanding of cardiovascular flows. [16][17][18] In response to the lack of datasets relevant to biomedical devices, the Food and Drug Administration (FDA) developed a benchmark model intended to validate CFD methodologies. This model produces challenging flow physics representative of those experienced in blood-contacting medical devices.…”