Numerical simulation of pulsatile flow through a coronary nozzle model based on FDA’s benchmark geometry

Abstract

Abstract:Computational fluid dynamics (CFD) is a powerful tool to extent knowledge of biomechanical processes in cardiovascular implants.To provide a standardized method the U.S. Food and Drug Administration (FDA) initialized a CFD round robin study. One of the developed benchmark standard models is a generic nozzle geometry, consisting of a cylindrical throat with a conical collector and sudden expansion on either side. Several fluid mechanical data obtained from international institutes by means of CFD and particle image velocimetry (PIV) measurements under different flow regimes (Re = 500, 2000, 3500, 5000 and 6500) are freely available.This database includes only steady state simulations. In this study we performed pulsatile CFD simulations to consider the physiological environment of the coronary vessels. Furthermore, the nozzle geometry was scaled down to coronary dimension (D inlet = 12 mm to 3 mm) while retaining the average Reynolds number Re = 500 constant. The pulsatile character is described by a Womersley number of Wo = 2.065. Our CFD code was previously validated by using FDA´s data for steady state inflow conditions. It could be shown that time averaged wall shear stress and shear stress values agree well with steady state results. We conclude that steady state simulations are valid for hemodynamic analyses if only time averaged values are needed. This could save computational costs of future hemodynamic investigations.In addition, this study expands FDA´s benchmark case by pulsatile inlet condition for further code validation. This could be necessary for the development of new numerical methods as well as for validation of CFD codes used in the approval process of medical devices.

CFD Computation of Flow Fractional Reserve (FFR) in Coronary Artery Trees Using a Novel Physiologically Based Algorithm (PBA) Under 3D Steady and Pulsatile Flow Conditions

“…Additionally, the PBA approach was verified using the benchmark model of the FDA nozzle. The goal was to replicate the study by Stiehm et al [19] using the PBA approach. The computational results of the axial velocity along the centerline of the nozzle geometry were compared to the CFD data from the FDA's round-robin study [19] for validation.…”

“…The normalization of the results was done to ensure comparability with the outcomes of the FDA's round-robin trial. The FDA nozzle in this study only used one cycle, as the same boundary conditions were already tested by Stiehm et al [19]. The convergence criteria are evaluated at the end of each iteration with equation ( 13).…”

Printability and Cell Viability in Extrusion-Based Bioprinting from Experimental, Computational, and Machine Learning Views

“…Experimental evaluation of the ink printability is time-consuming and costly, especially when bioink with expensive and sensitive cells is printed [ 114 ]. In this endeavour, computational methods as powerful tools provide information to bridge gaps between knowledge when clinical testing is difficult, expensive, time-consuming, or even impossible [ 115 ].…”

A bi-fidelity surrogate modeling approach for uncertainty propagation in three-dimensional hemodynamic simulations

“…Here, an idealized stenotic vessel geometry (3-D asymmetric nozzle) is considered, which was originally developed by the U.S. Food and Drug Administration (FDA) as a benchmark problem for a CFD round-robin study [86,87]. The nozzle geometry is scaled down to the coronary dimension (D in = 3 × 10 −3 m) [88], as shown in Fig. 2.…”

“…2. The setting of the baseline CFD simulation follows [88], where a unidirectional, To model the uncertainty in the inlet boundary condition, a stationary Gaussian random field f (x) is introduced to the streamwise (x−) component of the inflow velocity, which can be expressed as:…”