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arXiv 1011.3589math.NAcs.NAphysics.comp-phphysics.flu-dyn
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一种高效处理具有无滑移边界条件的不规则域上不可压缩Navier-Stokes方程的方法,直至边界的高阶精度

An efficient method for the incompressible Navier-Stokes equations on irregular domains with no-slip boundary conditions, high order up to the boundary

Massachusetts Institute of Technology(麻省理工学院)

David Shirokoff, Rodolfo Ruben Rosales

AI总结:

本文通过将不可压缩Navier-Stokes方程重新表述为速度-压力等价系统,并引入边界条件以明确从速度恢复压力,从而避免了投影法或分数步法中的矩阵分裂误差和边界误差,实现了直至边界的均匀收敛。

摘要:

常见的不可压缩Navier-Stokes方程的高效格式,如投影法或分数步法,由于矩阵分裂误差而具有有限的时间精度,或者在域边界附近引入误差(破坏了对解的一致收敛性)。本文将不可压缩(常密度)Navier-Stokes方程(边界上给定速度)重新表述为关于主变量速度和压力的等价系统。在远离边界处,我们通过用压力的泊松方程替换速度的不可压缩条件,以通常的方式实现。与通常方法的关键区别在于边界处,我们使用边界条件明确允许从任意固定时刻的速度恢复压力。这避免了通常出现的、看似超定的泊松问题的困难。由于在这种替代公式中,压力可以从速度准确且高效地恢复,因此重新表述的方程非常适合数值推进方法。新系统可以使用多种方法离散化,原则上可以达到任意期望的精度阶数。本文通过笛卡尔网格上的二维二阶有限差分格式说明了该方法,并设计了一种算法来求解具有弯曲(非一致)边界的域上的方程,包括具有非平凡拓扑的情况(域内的圆形障碍物)。该算法对速度和压力均实现了二阶精度(L无穷范数)。该格式自然可推广到三维。

英文摘要:

Common efficient schemes for the incompressible Navier-Stokes equations, such as projection or fractional step methods, have limited temporal accuracy as a result of matrix splitting errors, or introduce errors near the domain boundaries (which destroy uniform convergence to the solution). In this paper we recast the incompressible (constant density) Navier-Stokes equations (with the velocity prescribed at the boundary) as an equivalent system, for the primary variables velocity and pressure. We do this in the usual way away from the boundaries, by replacing the incompressibility condition on the velocity by a Poisson equation for the pressure. The key difference from the usual approaches occurs at the boundaries, where we use boundary conditions that unequivocally allow the pressure to be recovered from knowledge of the velocity at any fixed time. This avoids the common difficulty of an, apparently, over-determined Poisson problem. Since in this alternative formulation the pressure can be accurately and efficiently recovered from the velocity, the recast equations are ideal for numerical marching methods. The new system can be discretized using a variety of methods, in principle to any desired order of accuracy. In this work we illustrate the approach with a 2-D second order finite difference scheme on a Cartesian grid, and devise an algorithm to solve the equations on domains with curved (non-conforming) boundaries, including a case with a non-trivial topology (a circular obstruction inside the domain). This algorithm achieves second order accuracy (in L-infinity), for both the velocity and the pressure. The scheme has a natural extension to 3-D.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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