The classification of structured or unstructured grid is only by the book-keeping of the grid. ANSYS ICEM CFD can generate both structured and unstructured meshes using structured or unstructured algorithms which can be given as inputs to structured as well as unstructured solvers, respectively. Unstructured solvers can only work on an unstructured mesh even if provided with a structured-looking mesh created using structured/unstructured algorithm based meshing tools. On top of it, most of the popular CFD tools like: ANSYS FLUENT, ANSYS CFX, Star CCM+, OpenFOAM, AxSTREAM CFD, etc. Therefore, even if it creates a mesh that looks like a structured (single or multi-block) mesh through pain-staking efforts in geometry decomposition, the algorithm employed was still an unstructured one. For example, GAMBIT is an unstructured meshing tool. A mesh may look like a structured mesh but may or may not have been created using a structured algorithm-based tool. There are often some misunderstandings regarding structured/unstructured mesh, meshing algorithm, and solver. Structured C-grid around NACA0015 airfoil Each part can then be controlled for meshing, visualisation or various other purposes and is stored within the aforementioned tetin file. Geometrical entities which may include points, curves and surfaces must also be associated to a given part. Green: curve not attached to any surfaceĪn analysis post building the topology is then required, whereby if it is clear a curve is supposed to share two surfaces yet is being displayed as yellow, a hole exists and it is likely there will be meshing problems.BLUE: curve shared by more than two surface.YELLOW: curve attached to a single surface.The following is the colour coding in ICEM CFD, after the BUILD TOPOLOGY option has been implemented: Holes are typically identified through the colour of the curves. Existence of holes would mean that the algorithm which generates the mesh would cause the mesh to 'leak out' of the domain. It means if there is a source of water inside a region, the water should be contained and not leak out of the BODY.Īpart from the regular points, curves, surface creation and editing tools, ICEM CFD especially has the capability to do BUILD TOPOLOGY which removes unwanted surfaces and then you can view if there are any 'holes' in the region of interest for meshing. These maybe present due to differences in geometrical and meshing tolerances.There is hence an emphasis in ICEM CFD to create a mesh that has a 'water-tight' geometry. Negative volume elements are not permitted in external solvers. Regardless of this, the geometry should be checked using the geometry analysis to ensure the model contains a closed volume, meaning there are no holes or gaps within the geometry, so that further down the line, no negative volume elements are present.
For simple geometries the former tends to be used and for more complex geometries the latter is often used. ICEM CFD allows for its geometry to either be made using its own geometry topology package or to import geometry via external CAD software.
#ANSYS ICEM CFD MESHING SERIES#
The series of file types contained within the working directory are:
Every project will contain a series of file types dependent upon the mesh type and structure. It is possible to either create or open a pre-existing project.
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