http://icemcfd.com/icemcfd.html (World Wide Web Directory, 06/1995)
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.
ICEM CFD includes modules for generating:
Check out the Web pages for our newest products, ICEM CFD Hexa and IcePak.
Space shuttle mesh with 260,000 surface elements and 16.3 million volume elements.
Triangular mesh generated directly from the CAD surface geometry. The unstructured grid matches prescribed points and curves.
Throughout the design community, it's recognized that the earlier you know how a product will perform in real life, the lower the development and production costs. That's why analysis plays an ever-increasing role in today's design process. And, with concurrent engineering, computer simulations can eliminate physical prototypes and answer your questions about product performance.
As design problems become more and more complex, increasingly sophisticated analysis techniques must be employed. In the aerospace industry, for instance, existing designs are being modified and improved to produce quieter and more fuel-efficient products. In the automotive industry, design trends such as the cab-forward body style are placing increased demands on the car's cooling systems - both in the passenger compartment and under the hood. New product designs must allow manufacturers to maximize efficiency.
These increasingly sophisticated techniques require greater accuracy result ing in much larger analysis models - traditional mesh generators are not enough. Today, analysis experts can spend up to 80% of their time creating the analysis model alone. But more important is the time spent actually performing analysis and interpreting results.
ICEM CFD takes a new approach to pre-processing by allowing engineers to use the original 3D CAD geometry instead of building separate analysis model. Through an associative grid generation technique, based on a master model architecture, grids are created directly form CAD geometry - not just data from selected proprietary CAD systems, but from all popular CAD systems on the market.
With ICEM CFD, grids are generated independent of the CAD geom etry, then if it is necessary projected directly onto CAD surfaces. The patch-independent approach can overcome sharp edges, gaps, and overlaps in your CAD geometry. The resulting smooth grids lie directly on the CAD surfaces - producing very accurate results. Throughout the process, the engineer retains complete control of the grid characteristics and is supplied with a host of grid diagnostic and postprocessing tools. Unlike other grid generation tools available on the market, ICEM CFD eliminates the tedious tasks of meshing and stitching together individual CAD patches.
Grid characteristics are set up independent of the CAD geometry. Modifications to the master model are reflected through immediate regeneration of a new analysis model. This eliminates the need to reproduce geometry or modify grids to fit modified geometry, allowing you to take a more active role earlier on and throughout the design cycle.
Centrifuge CAD surface model.
Edge model: Nine domains with surface meshes.
Final structured mesh cross section.
Traditional Grid Generation methods versus ICEM CFD for Multi-Block Structured Grids
A grid generation system is measured not only by its algorithms, but also by the multi-block and complex grids which it generates. Today, ICEM CFD is being applied to wide variety of simulations in the aerospace, automotive, electronics and chemical industries.
The blocking strategy for any given situation may be approached in several ways. With ICEM CFD you can make decisions without limitations. Replace, merge, stretch options for block edges allow changes in CAD design to be reflected with full associativity to the grid topology model.
Space Shuttle shown in launch configuration. CAD data from a variety of formats and design teams are shown assembled in ICEM.
Multi-block configuration ensures complete topology and inter-block connectivity. Model shows meshed faces.
The Space Shuttle launch configuration has an extremely complex design. The close proximity of the Orbiter to the External Tank and Solid Rocket Boosters makes the grid generation task very critical in order to simulate the flowfield accurately. Here shown is the rear view of the aft attach hardware of the Shuttle Launch Vehicle.
Space shuttle pictures provided courtesy of NASA/JSC, NASA/AMES, Lockheed Space Division and Rockwell International.
Triangular and tetrahedral elements overcome many of the shortcomings of structured hexa hedral elements with respect to automatic mesh generation of complex geometry and local adaptive mesh refinement. For this reason, ICEM CFD also provides triangular/tetrahedral grids.
The user simply selects CAD geometry that specifies a volume to be meshed, and ICEM CFD automatically generates a triangular surface mesh and the inte rior tetrahedral mesh. Maximum element sizes can be defined on the surfaces and in volumes to reflect areas with high gradients in the flow field. The highly automated tetrahedral mesh does not need any triangular surface meshes as start grids, but works directly from the CAD surfaces using an octree-based approach. Smoothing algorithms provide element quality improvement when required.
CAD surface models can come from a variety of sources or can be generated within ICEM CFD. The surface model is used to describe volumes and voids to be meshed. Maximum element sizes can be specified for the selected surfaces and voids. Points and curves can be defined to specify exact placement of critical grid points and tetrahedral edges.
ICEM CFD meshes the volume by successive refinement until all mesh density requirements are met. The resulting tetrahedral mesh is an adaptive mesh of non-uniform density with well behaving elements. Tetrahedral meshing is done independent of the CAD surface patches and therefore is not dictated by the patch structure. Any modifications to the underlying CAD design can be reflected by simply regenerating the mesh with already existing set-up parameters.
Boundary conditions defined in the CAD model are applied to the resulting tetrahedral mesh. ICEM CFD supports RAMPANT by Fluent Inc., and FAST-Unstructured solver formats.
Some flow simulation solvers need a Cartesian or cylindrical discretization of the flow field. ICEM CFD generates grids based on CAD surface models in minutes. You can interactively define a box or cylinder around the CAD model and assign grid density and boundary conditions.
ICEM CFD automatically marks global Cartesian cells or cylindrical grids as inside or outside, or alternatively marks cells as containing a specific material. For cells cut by a boundary, you can calculate the percent occupancy of each material or decompose the cell into more complex elements conforming to the actual CAD surfaces. The result is a boundary fitted finite volume mesh.
ICEM CFD starts with excellent CAD capabilities that 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) for data exchange with other packages. Resulting grids, topology, inter-domain connectivity, and boundary conditions are stored in documented neutral formats. The user can then select a solver and an appropriate input file will be generated for that solver.
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
(510) 549-1890 / (510) 841-8523 FAX
Hexa WWW page by Vedat Akdag and Wayne Christopher.