All the grids have nearly the same total cell count, the number of points on the body, and a number of layers in the viscous padding and first spacing. Two-hybrid unstructured grids, 2 structured grids using GridPro, one cartesian grid using SnappyHex, and one polyhedral grid. Six grids were generated for the 2D NACA-0012 airfoil case. These are popular CFD validation cases in the aerospace community with reliable wind-tunnel experiments available for comparison.įigure 2: Computational domain around NACA0012 airfoil. The case of turbulent flow past a NACA-0012 airfoil and Onera M6 wing has been chosen for this exercise. The two flow problems discussed here can throw some light on the performance of some of the common gridding systems used in the industry. So the gridding approach adopted by a CFD practitioner depends on what his quest is, whether it is quality and accuracy of CFD solution or ease of grid generation or flexibility in handling parametric variants, etc, at the cost of other factors for his chosen CFD problem. Unfortunately, there is no universal gridding system to address all the above CFD requirements. Each element type has its inherent merits and demerits in their ability to handle complex geometries, time taken to generate the grid, ease of handling geometric variants, solver residual convergence levels achievable, quality and accuracy of the CFD solution obtained, etc. The key differences in the grids chosen for the exercise are the type of elements (structured, unstructured, cartesian, polyhedral) and the way in which they are arranged to fill the domain. This article compares standard test cases namely the NACA-0012 and the Onera M6 wing to throw light on the importance of a keen eye for the details in a CFD mesh. Unrelenting studies by many researchers show that no detail is too small. Nowadays discretization of a flow field for CFD goes by the idiom, do as you would be done by. Figure 1: Structured multi-block CFD mesh using GridPro for Onera M6 configuration with pressure fill contour.Ģ069 words / 10 minutes read Introduction
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