ICEM CFD is a powerful approach to pre-processing. Using associative grid generation techniques, it allows engineers to use existing 3D CAD geometry rather than building separate analysis models.
Hexa is a new object-based semi-automated hexahedral meshing module in ICEM CFD which provides rapid generation of multi-block structured or unstructured volume meshes.
The fast grid generation capability of ICEM CFD Hexa allows CFD engineers to respond to product design requests efficiently.
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ICEM CFD takes a unique approach to pre-processing by allowing engineers to use the original 3D CAD geometry created in any commercial CAD package instead of building separate analysis models.
With ICEM CFD, grids are generated directly on the CAD geometry, independent of the structure of the underlying CAD curves and surfaces. This approach produces smooth grids - with accurate results.
Unlike other grid generation tools available on the market, ICEM CFD eliminates the tedious tasks of meshing and stitching together individual CAD surface patches. It is also possible to generate a grid based on STL (Stereolithography) files or other triangular surface meshes, typically used in the early design stage.
Modifications to the master model are quickly reflected through regeneration of a new analysis model, allowing you to take a pro-active role in the design cycle.
ICEM HEXA represents a new approach to grid generation where the operations most often performed by experts are automated and made available at the touch of a button. The system includes powerful algorithms which allow users to generate high-quality grids in a fraction of the time that was previously required.
The user either defines the initial block structure, or HEXA will automatically initialize the block structure around a given geometry. Blocks can be interactively adjusted to the underlying CAD geometry. Body fitted internal or external O-Grids can be generated by the system automatically. The grid is projected onto the underlying CAD geometry with minimum user interaction.
Geometry shown has been brought into the ICEM CFD CAD-Mesher interface where the user assigns boundary condition names to CAD surfaces. This information is defined once and then reflected on the resulting computational grid.
The block structure is first initialized by the system and then subdivided into smaller blocks by the user. The user defines the material i.d.'s on the active blocks leaving others declared as non-active material.
The blocking structure shown was created using tools for splitting blocks and creating O-Grids. Model information can be saved at any stage. The O-Grids are automatically created after the user selects the blocks, faces and a scale factor value which controls the size of the O-Grid. The O-Grids shown inside the main duct and the auxiliary ducts are generated by simply selecting the region where the O-Grid should reside. These O-Grids are then automatically created and interfaced by the system.
Grid sizes are defined on the CAD surfaces by specifying the initial size, thickness and expansion rate from the surface. The grid distribution is calculated, the information set on the surfaces is matched,. and a smooth transition between blocks is automatically generated. Optional edge meshing operations can be performed on the individual block edges.
By default, ICEM CFD Hexa projects all block faces between different materials to CAD surfaces. In addition, block faces within the same material can be associated to thin walls. The user associates block edges to significant CAD curves. In some cases, the user may wish to move vertices onto the associated curves or CAD surfaces, or within the volume. ICEM CFD Hexa provides excellent interactive tools for moving vertices.
The user can choose to calculate the volume grid without projection. This option provides a rapid check of the current meshing strategy. The user can then calculate the volume grid with projection to CAD curves and surfaces. The resulting computational grid will reflect the exact geometry. With ICEM CFD Hexa, calculation time for a computational grid with 200,000 grid points is approximately 3 minutes, including projection to CAD surfaces, using a typical workstation. ICEM CFD Hexa provides sophisticated surface smoothing and volume relaxation algorithms. ICEM CFD Hexa also provides a set of tools for grid quality checking. The cells with undesirable skewness or angles can be displayed and proper block edges can be fixed interactively to obtain the best quality volume grid.
Shown above is the resulting volume grid, and a diagnostic check for grid skewness.
After the grid is calculated, it can be saved in multiblock structured or unstructured formats. The user then selects the analysis code. The computational grid combined with the boundary condition information is translated into an input file for the specific solver selected. ICEM CFD provides an interface to over 25 CFD and structural analysis codes currently used in the industry.
ICEM CFD starts with robust CAD capabilities which support the creation and modification of wireframe, 3D curves, regular surfaces and NURBS surfaces. It generates and receives standard open CAD formats (i.e., IGES, VDA/FS, SET, DXF and STL ) permitting data exchange with other packages. Resulting grids, topology, inter-domain connectivity, and boundary conditions are stored in documented neutral formats. The user then picks a solver from a menu and a required input file is generated.
ICEM CFD is available on HP, IBM, SGI, SUN workstations and X terminals connected to these workstations. Typical system requirements are 40 Megabyte of memory and 120 Megabyte of free diskspace to run ICEM CFD efficiently.
Trademarks: FLUENT, RAMPANT, Fluent Inc.; FIDAP, Fluid Dynamics International; TASCflow, Advanced Scientific Computing; VSAERO, Analytical Methods Inc.; STAR-CD Computational Dynamics Inc.; NS3D, Concordia University; AIRFLO3D, Texas Tech University; REFLEQS, CFD Research Corp.; FLOW3D, CFD Services Inc; NASTRAN, FAST-Unstructured, PLOT3D, NASA. SGI, Silicon Graphics Inc.; IBM, International Business Machines Co.; SUN, Sun Microsystems; HP, Hewlett-Packard Co. Any references to brands or trademarks are the property of their respective owners.
ICEM CFD Engineering / info@icemcfd.com
Berkeley office:
2855 Telegraph Ave Suite 501
Berkeley CA 94704
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Hexa WWW page by Vedat Akdag and Wayne Christopher.