Fluids – Fluid Dynamics Preprocessing for Complex Geometries

Meshing Large and Complex Geometries with Fluent Meshing

With ANSYS 16.0, Fluent Meshing is even more powerful and usable.

  • A new user interface on Fluent and Fluent Meshing give users a significantly better overview of their flow simulation set-up, making for much improved meshing workflow.
  • New mapped interfaces significantly improve the handling of non-conformal interfaces, giving the user much greater flexibility in mesh generation — without sacrifices in accuracy.
  • Multiple upstream meshes can now be combined in a Fluent system in Workbench, giving users the flexibility to select the most efficient mesh combinations for their application.
  • Geometry acquisition and model preparation are enhanced, with faster CAD import and numerous wrapping improvements; automatic closure of gaps between surfaces ensures that models can be readied for CFD simulation with a minimum of time and effort.

Engineers often deal with very large and complex geometries represented by CAD files or surface mesh files, which can have imperfections (holes or gaps that need to be closed before a fluid volume can be extracted). Resolution requirements can lead to large computational element meshes. Fixing all geometry imperfections manually requires a large number of corrections and expensive personnel time; creating these large meshes can be computationally time consuming. Perhaps the application in which this represents the largest challenge is for automotive Underhood Thermal Management (UTM) simulations. UTM geometries are highly complex and need powerful tools to be modeled efficiently and accurately, with a minimum of effort from the CFD engineer.

Fluent meshing has all the key technology needed to mesh complex or dirty geometry quickly: CAD import, hole and gap fixing, high-quality surface mesh creation and fast volume mesh creation. Fluent meshing has many advantages:

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Full automobile UTM simulation on the ‘world car’ — a representative generic full car model — showing resultant surface temperatures

  • Versatility: Either CAD or surface mesh can be imported.
  • Ease of use: Size functions, which capture model features, can be displayed to provide feedback that feature capturing is adequate. The user can save the size functions and re-use them directly whenever needed.
  • Built-in intelligence: Before volume meshing is done, diagnostic tools find and fix problems in assemblies (gaps or holes), face connectivities (faces overlapping or intersecting) and overall surface mesh quality.
  • Accuracy: Improved wrapping tools capture geometry features, and diagnostic tools determine how well the geometry features were captured. Various tools are available to further improve quality and accuracy of the wrapping when needed.
  • Speed:
    • Local surface remeshing tools locally improve surface mesh quality when needed, without having to remesh the entire geometry surface.
    • Volume meshing is faster (up to three times faster in prism layer generation).
    • Parallel meshing has excellent scalability when generating tet/prism meshes. Performance is case dependent, but 92 percent scalability has been observed on a 42-million-cell mesh when using eight cores.

Watch this video to see how to use the wrapper-based workflow to create high-quality CFD volume mesh. This video includes a description of how to use size field and create surface mesh.

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Underhood simulation with approx. 200 bodies, showing computed surface temperatures due to convective and radiative heat transfer from the exhaust manifold to surrounding objects

Watch this video to see how to interact directly with the Graphical User Interface (GUI) to prepare your CAD model for meshing: view and investigate your model, delete small parts when needed and simply the model by patching.