The analysis of Lax-Wendroff (LW) method is performed by the generic modified differential equation (MDE) approach in the spectral plane using Fourier transform. In this approach, the concept of dispersion relation plays a major role relating spatial and temporal dependence of the governing differential equation, including initial and boundary conditions in developing high accuracy schemes. Such dispersion relation preserving schemes are calibrated in the spectral plane using the global spectral analysis for the numerical method in the full domain. In this framework, the numerical methods are calibrated by studying convection and diffusion as the underlying physical processes for this canonical model problem. In the LW method spatial and temporal discretizations are considered together, with time derivatives replaced by corresponding spatial derivatives using the governing equation. Here the LW method is studied for the convection-diffusion equation (CDE) to establish limits for numerical parameters for an explicit central difference scheme that invokes third and fourth spatial derivatives in the MDE, in its general form. Thus, for the LW method, two different MDEs are obtained, depending on whether the LW method is applied only on the convection operator, or both on the convection and diffusion operators. Motivated by a one-to-one correspondence of the Navier-Stokes equation with the linear CDE established in "Effects of numerical anti-diffusion in closed unsteady flows governed by two-dimensional Navier-Stokes equation- Suman et al. Comput. Fluids, 201, 104479 (2020)", an assessment is made here to solve flow problems by these two variants of the LW method. Apart from mapping the numerical properties for performing large eddy simulation for the LW methods, simulations of the canonical lid-driven cavity problem are performed for a super-critical Reynolds number for a uniform grid.
翻译:Lax- Wendroff (LW) 方法的分析由光谱平面使用 Fleier 变换的通用修改差分方程式法(MDE) 进行。 在这种方法中, 分散关系的概念在管理差异方程式的空间和时间依赖性关系方面起着主要作用, 包括制定高精度计划的初始和边界条件。 这种分散关系保护方案在光谱平面上使用全域数值法的全球光谱分析来校准。 在这个框架中, 数字方法通过研究对流和扩散进行校准, 以作为这一卡通模型问题的基本物理进程。 在 LW 方法中, 空间和时间离异化被同时考虑, 时间衍生物被相应的空间衍生物取代, 使用调制式方程式进行相应的空间依赖。 LW 方法为明确的核心差异方案设定了数值参数, 以总体形式为MDE 的第三和第四个空间衍生物进行调值分析。 因此, 对于 LW 方法有两种不同的MDE 方法, 取决于 LW 方法是否仅对LW 流应用LVE 流进行双向LVe- deal- develildal- develop livaldal livaldal deal deal deal deal demodaldaldaldaldald ors ors,, lauts lauts lauts laut the lautdal- lauts laut lauts lautdal- deal- deal- demod livestodaltodaldal- devald lauts.