This utility is used to create a hex-core mesh inside any arbitrary volume defined by a surface mesh consisting of 2D first order elements: tria3 and quad4. The hex-core mesh can be created aligned with the global axes, or with any Cartesian local reference frame. The cell size along each coordinate axis is specified in the entries Hex-core cell size DX, DY, DZ and entries Core/bound clearance CX, CY, CZ control the minimum clearance between the hexa-core boundary and your specified surface mesh.  

Generated hexa elements are placed in a new collector named hexcore*. Pyramids are created on all the exterior quad faces of the hex-core mesh. Pyramids are placed in a new collector named pyramids*. Pyramids are created so that pyramids from faces at 90 degrees share the tip node, regardless of the value specified for the Pyramid’s height scale. Up to 3 pyramids can share the tip node. The pyramids’ height can be chosen as the shortest, average or longest side of the hex-core quad face base multiplied by the pyramid’s height scale.

The outer tria3 faces of the pyramids are placed in a new collector named faces_pyra_hex*. This component is used when the option Generate exterior tetrahedral mesh is not selected when the hex-core is created. This option is not selected by default as the tetramesh bridge typically takes much longer than the hex-core task and you may want to inspect the hex-core mesh before creating the tetrahedral mesh. Collector faces_pyra_hex* should be specified as fixed elements in the regular Tetramesh panel when generating the tetrahedral mesh bridge between the tria faces coming from the pyramids and the surface mesh (fixed or float) previously used to define the volume.

Boundary layer elements can be generated by activating the Boundary Layer check box and defining the required parameters in the bottom part of the HexCore tab.

The 2D surface elements that define the volume are selected using the Select Elems options and the Generate button is used to perform the actual mesh generation task.

If the checkbox Generate exterior tetrahedral mesh is activated, the check box for Surface mesh fixed can be activated as well. With this combination, the outer surface mesh is set as fixed during tetramesh generation and guarantees the connectivity between the tetras and the outer tria surface mesh. Use this option whenever you need to match other components to the tetra mesh, for example BL elements.

 

 

 

 

See Also:

CFD Meshing