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I think that gives enough context to start, so I’ll talk about how to actually set this up in SimScale now. To start editing the mesh settings, click Mesh in the left navigation panel.
General
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Mesh Settings + Geometry
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Primitives
That should bring up general global mesh settings, meaning that these settings apply everywhere in the domain. Change the algorithm from Standard to Hex-dominant parametric. This gives more control over the mesh and primarily uses hex-based elements rather than tet-based elements. Now expand the Geometry primitives section in the navigation panel and select the Background Mesh Box. A panel should open with the minimum x, y, and z coordinates, along with the maximum x, y, and z coordinates. I used minimum values of 0, 0, and -35, and maximum values of 5, 5, and 15. Next, select the Material Point section. This point determines which volume is divided into elements, so make sure the point is located within the background mesh box, but outside of the car geometry. While we’re here, add a Cartesian box geometry primitive. Select a region trailing from the car, for example 0, 0, -20 and 2, 2, -4. This is to enclose the wake behind the car. Return to the general mesh settings. Beneath the algorithm setting, there should be a section for Bounding box resolution. I’ve been using values of 16, 16, and 160.
You’ll notice that there are a bunch of settings beneath these if you scroll down. I consider these to be advanced settings, and the defaults usually work for most cases. Not our case though, as there are some settings that need to be changed. For now, scroll down to the Layer adding controls and turn off Layer size and I’ll return to this section later for the rest of the changes. ( The reason I make this change now is that it changes the meaning of some other basic settings that we are going to set next and then I prefer to tweak the advanced settings at the end, since they might take a few tries to get right).
General Refinements
Using a mesh that is 16x16x160 is not fine enough to represent the flow patterns around a vehicle. This is why refinements exist. Locate the Refinements section in the navigation panel, and begin by adding a bounding box refinement. Change the Face to Ymin, Min thickness to 1e-6 m, and Final thickness to 15e-3 m. Save the refinement by clicking the blue check mark in the top right of that panel. Add a region refinement. Change the Refinement mode to Distance and use the values from Table 1.
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