Aircraft unstructured mesh problem on density trailing edge
Hi friends,
I am doing an unstructured mesh around an aircraft. When I used the density on the trailing edge, I found there were still holes near it. So I continued to decrease the size in density function, then all of the mesh on aircraft body was disappeared. Does anybody know it? How to solve it? Many thanks! |
Adding pictures for the questions
2 Attachment(s)
Hi friends,
the first picture is the mesh I used the density bars in ICEM with size of 0.08. The second one which the body mesh disappeared is after I increased the density bar size to 0.05. If you guys know what happens, please let me know. Thanks |
did you use the feature "define thin cut" ?? if not, that's what you should use for the trailing edge. do a google search or a forum search for define thin cut. It has been discussed before
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By which method you are generating the mesh? top down octree or bottom up delaunay?
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Answer
Hi mate,
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Try using Patch Dependent along with Delaunay algorithm, and maybe you would have no such problems. |
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But octree method does not require surface mesh at all. So when you use octree you do not need surface mesh at all. Quote:
http://www.cfd-online.com/Forums/ans...rmula-one.html But I am not in favor of this method despite of its Awesome looking mesh. 1. It is slow method and you lose all advantages of ICEM which is famous for its top down approach. 2. You need high quality and well connected geometry which is not required by octree. 3. You need to define size on each and every curve. 4. Density boxes and size functions do not work with patch dependent surface meshing. Tetra meshing is successful, fat and accurate in ICEM (in first attempt) if you can properly define sizes and other options such as thin cut etc. |
I don't know why but ICEM always have problem in meshing curved leading and trailing edge surfaces of wings :confused:
If "Define Thin Cuts" is not solving your problem then I suggest another method. Split the surfaces of wings at some distance from leading edge and trailing edge both. Now you have three surfaces on the suction side and three surfaces on the pressure side. Mesh the two surfaces near leading edge(suction and pressure side) and two surfaces near trailing edge(suction and pressure side) with either Patch Dependent Method or by Autoblock method. Go to Compute Mesh and compute only the surface mesh on these 4 surfaces. Apply other settings on parts and surfaces, densities as normal. Now again go to compute mesh and calculate Volume Mesh by Octree Method by selecting " Use Existing Mesh Parts" . During the process Octree works as normal but in the end replace the mesh on these surfaces with Patch Dependent or Autoblock method. By this way you will have a nice surface mesh adapting to the curvature of the geometry. After this you can replace the volume mesh with Delaunay and insert prisms according to your requirements. I hope I have made myself clear but if you have doubts come back again, I will post a pic about the procedure of the method. |
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