Force-amplified, single-sided diffused-interface immersed boundary kernel for correct local velocity gradient computation and accurate no-slip boundary enforcement
Force-amplified, single-sided diffused-interface immersed boundary kernel for correct local velocity gradient computation and accurate no-slip boundary enforcement
复制标题
力放大、单侧扩散界面浸入边界内核，用于正确的局部速度梯度计算和精确的无滑移边界执行
DOI：
10.1103/physreve.101.053305
复制
发表时间：
2020
影响因子：
2.4
通讯作者：
Wang Lian-Ping
中科院分区：
文献类型：
--
作者：
Peng Cheng;Wang Lian-Ping
目前采用双面力分布核的扩散界面浸入边界法不能正确计算扩散界面内的速度梯度。这是因为分布在流体节点上的非零边界力修改了由Navier-Stokes方程（nse）在这些位置解出的动量方程。本文对简单平面流道流动中的这一问题进行了解析求解。采用单面力分布核来限制固体区域的边界力，恢复流体区域的nse，以保证正确的速度梯度计算。为了提高IBM系统的无滑移边界执行能力，提出了一种非常简单的力放大技术。该技术不需要额外的计算成本，并且可以显著减少必要的迭代，以实现精确的无滑移边界强制。单面核和力放大技术分别在层流和湍流中进行了检验。与标准的IBM方法相比，所提方法不仅在固体表面附近得到正确的速度梯度结果，而且减少了流速和水动力和扭矩结果的数值误差。
The current diffused-interface immersed boundary method (IBM) with a two-sided force distribution kernel cannot be used to correctly calculate the velocity gradients within the diffused solid-fluid interfaces. This is because the nonzero boundary force distributed to the fluid nodes modifies the momentum equation solved at these locations from the Navier-Stokes equations (NSEs). In this paper, this problem is analytically identified in simple plane channel flow. A single-sided force distribution kernel is used to restrict the boundary force in the solid region and restore NSEs in the fluid region for correct velocity gradient computation. In order to improve the no-slip boundary enforcement in IBM, an extremely simple force amplification technique is proposed. This technique requires no additional computation cost and can significantly reduce the necessary iterations to achieve accurate no-slip boundary enforcement. The single-sided kernel and the force amplification technique are examined in both laminar and turbulent flows. Compared to the standard IBM, the proposed methods not only produce correct velocity gradient results near a solid surface but also reduce numerical errors in the flow velocity and hydrodynamic force and torque results.