Fluid dynamics of human thoracic aorta: Three-dimensional computational fluid dynamics simulations coupled with comprehensive modeling of remaining blood flow network including the heart

The paper is a comprehensive documentation of the complexity, and the spatial and temporal variations of flow field in human thoracic aorta during a cardiac cycle, determined through rigorous application of computational fluid dynamics, requiring several innovative measures in the adopted multiscale approach. Detailed physical discussion of the fluid dynamics is provided. Three-dimensional geometry is constructed from Computed-Tomography-scan data. The Windkessel model with optimum parameters is applied separately at each of the five outlets, thus capturing the influence of blood flow network outside the computational domain. An improved heart model is implemented at the inlet boundary. Shear-Stress-Transport k−ω with intermittency transition model is used. Simultaneous presence of forward and reverse flow on same cross section is captured accurately. An extensive quantitative visualization is achieved by presenting distributions of primary velocity on carefully selected 25 cross-sectional planes at eight distinctive instants of cardiac cycle. The distribution of wall shear stress is revealed. Several flow features observed in in vivo measurements are captured. Computed waveforms agree quantitatively with measured waveforms of both pressure and flow rate during a complete cardiac cycle; in the past, researchers attempted to match only systolic and diastolic pressures. Present computations can predict smooth dicrotic notch and correct timings of its occurrence. Computations reveal regions of considerable reverse flow on many cross sections during a large part of cardiac cycle, even when the net flow through such sections is positive. Computed relative proportions of flow through four supra-aortic branches and descending aorta relate well to similar proportions found in the clinical data.