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#1 |
New Member
Join Date: Mar 2024
Posts: 2
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Very new to CFD and looking into using an active flow control blowing actuator to analyse flow separation, and lift/drag coefficients. Used a baseline NACA0012 aerofoil to get 2D simulation results, I generated a 2D mesh, using calculated values to set prism layer thickness, for a Y+ = 1 and the results were accurate when compare to current research and javafoil estimations.
I have created a CAD model of the modified aerofoil (i.e. with a slot cut into the surface to be used as an additional velocity inlet, imported into STAR CCM with no issues. Due to positive results with initial baseline mesh, I have tried to marry this mesh across to the new modified part, however, I lose the prism layers at the point at which the slot is cut into the surface. I ran a simulation anyway and the lift/drag values are way off what I was expecting (CL is 1.2 at 1Deg AoD, when I was expecting 0.1 ish). Lead me to believe the loss of prism layers are causing the spurious results. To rectify, I have tried reducing the stretch factor of the mesh, minimum thickness size, number of layers etc. and also surface mesh. I have tried using a volumetric control by pinpointing the affected area with a cylinder or a block and controlling the mesh that way, each method has failed me. Does anybody have any ideas as to how I can refine this troublesome area? Many thanks Attachments - Baseline Mesh Domain Baseline Mesh Leading Edge Close Up Modified NACA0012 Close Up Modified NACA0012 Mesh NACA0012 Modified CAD Close Up.jpg NACA0012 Modified.jpg Baseline Mesh 1.jpg Baseline Mesh.jpg |
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#2 | |
Senior Member
Chaotic Water
Join Date: Jul 2012
Location: Elgrin Fau
Posts: 437
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Quote:
You can override that with Surface Control at slot surface (check Override option and set Prism Layers parameters). |
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#3 |
New Member
Join Date: Mar 2024
Posts: 2
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Many thanks for the quick response, I’ve managed to refine the gap as much as I can although whe I have assigned the surface control to the slot inlet with specified prism layer parameters, no prism layers are created, which I can’t understand wh
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#4 |
New Member
Join Date: Mar 2011
Posts: 20
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If I understand correctly, you are modeling your outlet just as a surface patch. This will always result in the prism layers collapsing. I would actually model a small section of the slot in the CAD, so "into" your airfoil. By this, you would have a segment of the channel inside the airfoil resulting in the prism layers to follow the surfaces including the sharp edges.
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Tags |
mesh 2d, prism layer meshing, star ccm+ mesh |
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