Direct immersogeometric fluid flow analysis using B-rep CAD models
Direct immersogeometric fluid flow analysis using B-rep CAD models
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DOI：
10.1016/j.cagd.2016.02.007
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发表时间：
2016-03-01
影响因子：
1.5
通讯作者：
Krishnamurthy, Adarsh
中科院分区：
文献类型：
--
作者：
Hsu, Ming-Chen;Wang, Chenglong;Krishnamurthy, Adarsh
我们提出了一种浸入式几何流体流动分析的新方法，该方法直接使用复杂物体的CAD边界表示（B-rep），并将其浸入到流体域的局部精炼、非边界拟合离散化中。激励应用包括分析复杂几何形状的流动，例如移动的车辆，其中详细的几何特征通常需要耗时，劳动密集型的几何清理或网格操作，以生成周围的边界拟合流体网格。所提出的方法避免了与此类程序相关的挑战。提出了一种对背景网格正交点进行隶属度分类的新方法。为了忠实地捕捉相交元素中的几何形状，我们实现了一种基于元素递归分割的自适应正交规则。在相交元素中的狄利克雷边界条件在尼采方法的意义上是弱的。为了评估所提出方法的准确性，我们对用B-rep表示的球体上的流的基准问题进行了计算。感兴趣的量，如阻力系数，与文献报道的参考值很好地一致。结果表明，表面正交点的密度和分布对于弱执行狄利克雷边界条件和获得精确的流动解至关重要。此外，在足够的曲面正交单元精化水平下，切边曲线附近的正交误差变得微不足道。最后，通过对使用B-rep直接表示的农业拖拉机进行气动分析，我们证明了浸入式几何方法在高保真工业规模模拟中的有效性。(C) 2016 Elsevier B.V.版权所有
We present a new method for immersogeometric fluid flow analysis that directly uses the CAD boundary representation (B-rep) of a complex object and immerses it into a locally refined, non-boundary-fitted discretization of the fluid domain. The motivating applications include analyzing the flow over complex geometries, such as moving vehicles, where the detailed geometric features usually require time-consuming, labor-intensive geometry cleanup or mesh manipulation for generating the surrounding boundary-fitted fluid mesh. The proposed method avoids the challenges associated with such procedures. A new method to perform point membership classification of the background mesh quadrature points is also proposed. To faithfully capture the geometry in intersected elements, we implement an adaptive quadrature rule based on the recursive splitting of elements. Dirichlet boundary conditions in intersected elements are enforced weakly in the sense of Nitsche's method. To assess the accuracy of the proposed method, we perform computations of the benchmark problem of flow over a sphere represented using B-rep. Quantities of interest such as drag coefficient are in good agreement with reference values reported in the literature. The results show that the density and distribution of the surface quadrature points are crucial for the weak enforcement of Dirichlet boundary conditions and for obtaining accurate flow solutions. Also, with sufficient levels of surface quadrature element refinement, the quadrature error near the trim curves becomes insignificant. Finally, we demonstrate the effectiveness of our immersogeometric method for high-fidelity industrial scale simulations by performing an aerodynamic analysis of an agricultural tractor directly represented using B-rep. (C) 2016 Elsevier B.V. All rights reserved.