In this paper, we investigate the hemodynamics of a left atrium (LA) by proposing a computational model suitable to provide physically meaningful fluid dynamics indications and detailed blood flow characterization. In particular, we consider the incompressible Navier-Stokes equations in Arbitrary Lagrangian Eulerian (ALE) formulation to deal with the LA domain under prescribed motion. A Variational Multiscale (VMS) method is adopted to obtain a stable formulation of the Navier-Stokes equations discretized by means of the Finite Element method and to account for turbulence modeling based on Large Eddy Simulation (LES). The aim of this paper is twofold: on one hand to improve the general understanding of blood flow in the human LA in normal conditions; on the other, to analyse the effects of the turbulence VMS-LES method on a situation of blood flow which is neither laminar, nor fully turbulent, but rather transitional as in LA. Our results suggest that if relatively coarse meshes are adopted, the additional stabilization terms introduced by the VMS-LES method allow to better predict transitional effects and cycle-to-cycle blood flow variations than the standard SUPG stabilization method.
翻译:在本文中,我们通过提出一个适合提供具有物理意义的流体动态指示和详细的血液流特征的计算模型,调查左 ⁇ (LA)的热动力学。我们特别考虑到Ardicli Lagrangian Eulerian (ALE) 的不可压缩的纳维-斯托克斯方程式的配方,以便根据规定动议处理LA域。我们采用了一种变化式多级(VMS)法,以获得通过精度元素法分解的纳维-斯托克斯方程式的稳定配方,并计算出基于大型湿度模拟(LES)的动荡模型。本文的目的有两个方面:一方面是增进对正常条件下人类LA血液流的一般理解;另一方面是分析VMS-LES方法对血液流状况的影响,这种情况既不是薄度,也不是完全动荡,而是像LA那样是过渡性的。我们的结果表明,如果采用相对均匀的模,那么VMS-LES方法引入的额外稳定化条件就能够更好地预测稳定性变化,而不是SUPGI标准周期周期。