Mesh refinement can also be automatically introduced to improve feature definition in any part of the model. This is achieved through the use of a novel feature classification process which allows the Engineer to identify important parts of the model.

Further enhancements to samm include an advancing front tetrahedral mesher, plus a combined hexa/tetrahedral mesher called the “hybrid” scheme. In all instances, samm can include the near wall layers essential to accurate CFD modeling.

Incorporating samm into the normal analysis environment is also seamless, as it is developed by the same Engineers that develop PROSTAR for STAR-CD. Familiarity with STAR-CD functionality automatically provides the CFD Engineer with a tool which he or she already understands, minimizing learning time and optimizing productivity.

Features:

A summary of the features in the current samm release is given below:

CAD Interfaces:
- Interfaces with most popular CAD formats including STL, NASTRAN, PATRAN,VDA,IGES and IDEAS
- Direct compatibility with PROSTAR

Surface preparation tools:
- Surface fixing and cutting tools
- New surface generation
- Surface wrapper
- Surface smoother and refinement

Subsurface Generation:
- Alternative algorithms for differing model complexity
- Variable subsurface thickness for y+ control

Mesh Generation:
- Improved samm polyhedral mesh cutting
- All tetrahedral mesher (including prismatic layers)
- Hybrid meshes (combined hexahedral/tetrahedral mesh)
- Advanced volume smoothers
- Custom (user defined) mesh option

Refinement:
- Automatic classification and refinement of important features
- Mesh coarsener

GUI:
- Process oriented GUI panel to guide user
- samm Mesh Wizard for novice and occasional users
- Database facility for storing and retrieving meshes

Some of the above features are demonstrated bellow using worked examples.

The samm Mesh Wizard

The samm Mesh Wizard provides the novice or occasional samm user with a simple step-by-step meshing process to guide them through all the actions required to make a grid.

	The first wizard guides the user through importing CAD surface data.
A new surface (better than the origonal) can then be made.
	A subsurface is made from the new surface, a specified distance from the origonal.
A samm mesh can then be made based on on single parameter (the cell length).

samm Panel GUI

The samm Panel GUI includes all the advanced meshing options in simple to use process oriented panels.

All Samm panels follow a consistent format and automatically update information based on the last action performed.

Surface Preparation

Surface preparation tools allow the user to fix any surface deformities or even create a new closed surface based on the original geometry.

The original IGES data here is mismatched and has holes. The edge zipper and hole filler in samm can be used to make a fully closed connected surface.
The surface checker is used to highlight any problems in the origonal surface by using red marker cells. These problems can be fixed by hand or automatically by samm itself.	If a higher quality surface is desired, a new surface can be created for whole or part of the origonal model.

Surface Wrapper

In cases where the original CAD geometry is poorly defined (holes, overlaps etc), a surface wrapping technique can be used to provide a closed surface definition.

	The starting point for the surface wrapper is a "classified" block allowing internal, external, and surface section cells to be identified
	Successive refinement of the intersecting cells builds up a stair-stepped grid that closely follows the origonal surface
When the required cell size is reached, the external star-step surface is mapped onto the origonal to provide a new closed surface definition, ready for use in samm.

Example samm Mesh

An example samm grid is shown below. This is a manifold body that was meshed using 150,000 cells. It contains two layer of cells next to all the wall surfaces.

Additional Features

Refinement, custom meshes and variable subsurfaces can also be included.

	The variable subsurface control allows thinner near wall cells (above), while classification and refinement provides high feature definintion at a low cell count.

Tetrahedral Meshing

A new advancing front tetrahedral mesher included in samm allows all tetrahedral meshes to be created, including prismatic layers. Hybrid (hexa/tetra) meshes are also possible for optimal mesh control and efficiency

The surface reconstruction scheme rebuilds a better quaility surface for meshing.
Internal features, such as pourous media interfaces are allowed within the tetrahedral mesh.
A smoother improves the quality of the surface but leaves the surface features intact.

Hybrid Meshing

This new technique combines the existing hexahedral classification technology with the automatic advancing front tetrahedral mesher. The result is an optimized CFD grid composed of hexahedral, pyramid, tetrahedral and prismatic cells. No cell matches are required and local refinement can be included afterwards using PROSTAR.

This fully automatic procedure provides a predominantly hexahedral mesh which is ideal for solution convergence and accuracy. The method can be combined with the user mesh capability in order to further enhance the solution characteristics of the model.

An example section slice of the hybrid method is shown below:

	Prismatic Extrusion Layer
	Tetrahedral Fill
	Pyramid Transition Layer
	Core Hexa Cells

Coming soon is a new meshing product, pro*am. pro*am will combine in one easy package all the automatic meshing features of samm, our new automatic tetrahedral mesher and the powerful features of PROSTAR.

In addition to the automatic mesh generation features, pro*am will provide the user with quality surfacing, surface repair and sub-surface generation capabilities.

Look for pro*am in May 2000!

For more information on any of the products mentioned, please contact:

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email us at:info@adapco.com