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  • [ October 15, 2018]

    A new hybrid viscous mesh generation method presented by Jianfei Liu’s group

  • Recently, International Journal for Numerical Methods in Engineering, the top journal on computational mechanics, published an article of Prof. Jianfei Liu's group, entitled 'Automatic and efficient hybrid viscous mesh generation based on clipped Voronoi diagrams'.

    Mesh generation is the key step for numerical simulations in Computational Fluid Dynamics(CFD). However, generating valid meshes for practical engineering problems with complex geometric configurations is still a tough task. And this task turns more difficult for viscous flow problems where boundary layers at the wall must be considered.

    Typically, the hybrid viscous mesh generation is separated into the following two parts: one utilizing advancing layers method for the boundary layer meshes and the other utilizing the isotropic generator for the far field meshes. The two-step advancing layers method is widely used, which has nicely addressed a lot of practical problems. However, this method still suffers some problems in dealing with the complex boundary features such as the narrow gaps. Meshes are going to worsen heavily, sometimes get invalid, where advancing fronts from different wall surfaces intersect or the boundary layer meshes transit into the far field meshes. It will take a large number of artificial work to modify and adjust these poor meshes.

    To overcome the drawbacks of the two-step advancing layers method, a novel method for hybrid viscous mesh generation was presented by Liu’s group. The new method is based on the theory of Voronoi diagrams. The boundary layer mesh and the far field isotropic mesh are generated simultaneously in one step after the Voronoi seeds are appropriately arranged. In their method, advancing fronts from different wall surfaces can be merged automatically. And the transition mesh elements between the boundary layer meshes and the far field meshes are in high quality, which heavily decreased the inefficient artificial work.

    The anonymous expert referee made very encouraging comments: "The paper represents an important advance in the field of mesh generation for viscous flows". Since CFD has developed rapidly in the past few decades and is widely used for computational design, analysis and optimization, this comment is really a high praise.

     

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    Figure 1. Viscous mesh for the simulation of flow past the RAE 2822 airfoil

    Figure 2. Viscous polyhedral mesh for the simulation of flow past a cylinder

     

    Figure 1 and Figure 2 show respectively the viscous meshes generated by the new method for the simulations of viscous flows past the RAE 2822 airfoil and a cylinder.

    This work was completed under the direction of Prof. Liu. The first author of the article is Yangke Gan, a doctoral candidate from the College of Engineering. His research interests include mesh generation and mesh optimization.