OECD/NEA-Vattenfall T-Junction Benchmark
The T-Junction mesh was generated for the OECD Vettenfahl T-Junction benchmark; this exercise was a blind benchmark of various CFD codes. The Argonne code Nek5000 participated in this benchmark, using the mesh shown below. The mesh was generated with Cubit 10.2, then modified to extend the (top) inflow and (side) outflow pipes.
Cutaway view of volume mesh
Shape quality metric for this mesh. Probably low due to
high aspect-ratio elements in boundary layer.
Adding Boundary Layers Using MeshKit’s PostBL Tool
Figure (a) shows the original model, figure (b) shows a zoomed-in view of the T-junction in the original mesh. MeshKit‘s PostBL tool uses only one normal direction on this T-intersection point to create new boundary layer elements; this allows for creation of a smooth mesh with similar-sized elements. The shape quality metric of this mesh is shown in Figure (c); elements with lower but acceptable quality elements are on the boundary because of low aspect ratio of the mesh. A close-up in Figure (d) shows three new layers as a separate material.
Hex meshed T-junction example: (a) Original mesh. (b) Close-up of original mesh intersection of cylinders. (c) Mesh with 3 boundary layers showing shape quality metric, smoothened using MESQUITE. (d) 3 boundary layers mesh close-up.