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当地DFD方法向LES湍流模拟推广的研究
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作者 徐振东 段宇轩 +2 位作者 徐华松 杨帆 李铁 《空天防御》 2022年第3期93-98,共6页
为有效地降低近壁面网格分辨率的要求,将一种被称为当地自由域离散化(domain-free discretization,DFD)方法的浸没边界法(immersed boundary method,IB)与大涡模拟(large eddy simulation,LES)相结合模拟湍流。偏微分方程在解域内节点... 为有效地降低近壁面网格分辨率的要求,将一种被称为当地自由域离散化(domain-free discretization,DFD)方法的浸没边界法(immersed boundary method,IB)与大涡模拟(large eddy simulation,LES)相结合模拟湍流。偏微分方程在解域内节点上的离散形式可能包含解域之外的节点,外部相关点处的流动变量通过沿垂直于壁面方向的线性外推进行估算。引入基于湍流边界层方程的平衡型壁面模型,壁面模型产生的壁面剪应力和无穿透条件在浸没边界处强制执行,以计算外部相关节点处的速度分量。对于湍流闭合,采用动态亚网格尺度(subgridscale,SGS)模型,并使用拉格朗日平均法计算模型系数。外部相关节点处的SGS涡流黏度为外层处的涡流黏度。为验证当前LES-DFD方法的能力,在相对粗的网格上进行了后台阶绕流的数值实验。计算结果与已发表的实验或数值结果非常吻合。 展开更多
关键词 浸没边界法 大涡模拟 当地自由域离散化方法 湍流 壁面模型
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Simulation of Incompressible Viscous Flows by Local DFD-Immersed Boundary Method
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作者 Y.L.Wu C.Shu H.Ding 《Advances in Applied Mathematics and Mechanics》 SCIE 2012年第3期311-324,共14页
A local domain-free discretization-immersed boundary method(DFDIBM)is presented in this paper to solve incompressible Navier-Stokes equations in the primitive variable form.Like the conventional immersed boundary meth... A local domain-free discretization-immersed boundary method(DFDIBM)is presented in this paper to solve incompressible Navier-Stokes equations in the primitive variable form.Like the conventional immersed boundary method(IBM),the local DFD-IBM solves the governing equations in the whole domain including exterior and interior of the immersed object.The effect of immersed boundary to the surrounding fluids is through the evaluation of velocity at interior and exterior dependent points.To be specific,the velocity at interior dependent points is computed by approximate forms of solution and the velocity at exterior dependent points is set to the wall velocity.As compared to the conventional IBM,the present approach accurately implements the non-slip boundary condition.As a result,there is no flow penetration,which is often appeared in the conventional IBM results.The present approach is validated by its application to simulate incompressible viscous flows around a circular cylinder.The obtained numerical results agree very well with the data in the literature. 展开更多
关键词 local domain free discretization(local dfd) immersed boundary method(IBM) incompressible flow flow past a circular cylinder
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