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Need help understanding mesh

    • Nick Makaroglou
      Subscriber

      Hello all, let me preface by saying I am new to Ansys and it's capabilities. In the few videos I have seen when it comes to mesh, they do things differently. What I mean is that some simply generate the mesh, others in the "Element Size" cell, they put a small number (like 5mm). Others in the "Sizing tab", they put "Fine" in the "Span Angle Center". To me those two things are the same. Are they needed? Which one is let's say necessary to have better results. Also in another video, this one "https://www.youtube.com/watch?v=zPI3-dyvpEY", they click insert "method", which creates "automatic method" in the mesh and then they click the whole body and also the insert "sizing" and then they click the corners. My question is, what's the point of all of that and are they needed? What do those extra insertions do to the end result?

      Thank you to all who answer!

    • Nanda Veralla
      Ansys Employee

      ANSYS offers several meshing techniques to discretize and mesh geometries for analysis. The specific meshing method used depends on the geometry type, analysis type, and user preferences. Here are some common meshing techniques employed by ANSYS:

      1. Automatic Tetrahedral Meshing: Typical applications of this algorithm include conventional 3D solid geometries. Tetrahedral elements are automatically generated by ANSYS volume-based meshing method, which discretizes the geometry. It begins with a rough mesh and then adjusts it according to user-defined standards such element size, curvature, and aspect ratio
      2. Automatic Hexahedral Meshing: ANSYS can create a structured hexahedral mesh automatically for specific regular and well-defined geometries. In some circumstances, hexahedral components offer greater precision and effectiveness. By lining up objects with geometrical characteristics, edges, and faces, the programme tries to produce an organised mesh
      3. Surface Meshing: In some circumstances, such as for 2D simulations or when utilising shell components, just the geometry's surfaces need to be meshed. Surface meshing methods from ANSYS produce triangular or quadrilateral elements on the surface of the geometry. To generate a complete 3D mesh, these components can be merged with different meshing techniques
      4. Sweep Meshing: For geometries having axisymmetric or extrusion characteristics, this method is helpful. To produce a 3D mesh, ANSYS may sweep a 2D mesh along an axis or route. It is frequently employed in rotational symmetry-based simulations, such as heat transfer or fluid flow assessments
      5. Patch Conforming Meshing: When working with intricate geometries or assemblies, ANSYS gives customers the option to individually produce mesh patches for various geometries. This method gives more control and flexibility in meshing distinct model components. When the geometry has areas with considerably differing meshing needs, patch conforming meshing might be helpful.
      6. Mesh Adaptation: According to the outcomes of the solution, ANSYS provides mesh adaption algorithms that can fine-tune or coarsen the mesh. In areas of interest, the mesh density can be automatically changed to increase precision or productivity. In simulations when there are places with noticeable variations in the solution gradients, mesh adaptation can be especially helpful.

      These are just a few examples of the meshing techniques available in ANSYS. The software provides a wide range of meshing options and customization features to accommodate different analysis requirements and geometry types. The specific steps and options for meshing a geometry in ANSYS can vary depending on the version of the software and the modules being used. All these extra insertions, make your model computationally efficient and accurate. Let's consider for example, you need to simulate a fracture growth of a flat plate. Fracture growth requires very fine mesh at the crack tip, so if you mesh whole model with fine mesh, you end up with millions of nodes and it takes lot of time for ANSYS to solve the model. For the same case, if you a local mesh control such as "sphere of influence" and make a coarse mesh elsewhere, the computational effort is reduced significantly.

      I'm sharing couple of links on meshing, which will provide you on how ANSYS discretizes it's geometry:

      Numerically Accurate Results - ANSYS Innovation Courses

      Mesh Controls Overview (ansys.com)

      Regards,

      Nanda.

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    • Ashish Khemka
      Forum Moderator

      Hi Nick,

      I do not see a need for an automatic method. You can try a sphere of influence/ refinement at fillet regions. Avoid face meshing at fillets - they give good surface elements but elements remain coarse beneath the surface.

      Regards,

      Ashish Khemka

       

       

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