About SC/Tetra - Pre-processor

PRE-PROCESSOR | POWERFUL MESH GENERATOR | SIMPLE SETTING

Pre-Processor

The SC/Tetra preprocessor uses geometry data created by a CAD designer or an existing surface mesh created by other modeling applications to generate a computational volume grid in the space where the fluid flows.   Our preprocessor rapidly constructs an optimized volume mesh even for the most complex geometries. Moreover, SC/Tetra offers a user-friendly environment (including set-up wizards and automatic adaptive control) while still providing the user maximum control of the mesh parameters when needed.

INTERFACE

The SC/Tetra preprocessor can read in geometry or surface mesh data in a variety of formats. In addition, SC/Tetra can directly export surface variable distributions (e.g. heat transfer coefficients or gas temperatures) from the CFD analysis to Finite Element Analysis (FEA) thermal stress analysis software, such as ANSYS and I-DEAS. Mapping functions enable translation of surface parameters from the CFD mesh to elements on the FEA (solid) model even though the two meshes are different.

PRE-PROCESSOR | POWERFUL MESH GENERATOR | SIMPLE SETTING

Powerful Mesh Generator

HIGH SPEED

SC/Tetra’s high speed mesh generation capabilities are achieved by proprietary implementation of the Advancing Front Method. The power of this method can be clearly seen with a 5,000,000 element mesh being generated in 33 minutes using a late model Pentium III (1GHz) PC. If you need to re-mesh, you can specify an arbitrary area for mesh correction using an already created mesh. This significantly reduces the time for mesh generation.

MESH COMPLEX SHAPES

The SC/Tetra preprocessor can generate large-scale meshes for highly complex geometries. Underhood engine compartments (including the full external vehicle shape) is an example of they kinds of complex geometries that are commonly analyzed today. With today’s powerful computers SC/Tetra can model the entire vehicle without having to break it into separate pieces. For more information see "Development of Underbody Aerodynamic Simulation Using Automatically Generated Tetrahedral and Prismatic Cells" Japanese Society of Automotive Engineers, Fall 2000 Congress Proceedings, Paper# 20005453(2000)

AUTOMATIC STL CORRECTIONS

STL format (polygon) data is commonly used as CAD input data for SC/Tetra. However, several instances occur where the STL data is not well constructed. Extra polygons may have been created or polygons may have been inadvertently lost creating holes. SC/Tetra offers an automatic STL correction function which corrects these errors using a single menu command. If the input data requires more modifications, SC/Tetra offers a wealth of geometry and grid correction tools. These functions are integrated within the SC/Tetra preprocessor and have capabilities that rival 3rd party specialty grid generation software (which usually costs an additional $ 10,000 per year to lease).

HYBRID MESH - PRISM ELEMENTS

A major improvement in near wall (boundary layer) solution accuracy can be achieved by properly arranging the triangular pillar shaped (prism) elements near the wall It is usually very important to precisely model the boundary layer in numerical simulations especially if near wall parameters (e.g. heat transfer coefficient) will be used as outputs from the CFD simulation. The calculation accuracy will be improved by properly arranging thin prism layers near the wall. When inserting the prism layers, their thickness is a very important factor that determines both the accuracy and efficiency of the calculation. Although boundary layer thickness can be estimated analytically from the main flow velocity, a more effective method is to use turbulence-scaling lengths from the turbulent flow calculations. If the adaptive mesh refinement function within SC/Tetra is used, the optimized thickness of the prism layers is automatically calculated.

PRE-PROCESSOR | POWERFUL MESH GENERATOR | SIMPLE SETTING

Simple Settings

AUTOMATIC ADAPTIVE MESH REFINEMENT

Using SC/Tetra’s adaptive mesh refinement function, an appropriate, optimized mesh will be created automatically for flows with large gradients. The total size of the model can be constrained by specifying the target number of total elements. SC/Tetra uses solutions obtained from coarser meshes and progressively refines the mesh in areas of large gradients. Automatic adaptive mesh refinement greatly reduces the number of man-hours required to obtain a precise solution since no extra settings are required. In addition to shortening the total computation time, compared to a conventional refinement approach using manual operations, the meshes created by this adaptive algorithm do not depend on operators' experience. This enables a new user to obtain same quality of solution as the experts.

WIZARD GUIDED SETUP

Easy to use set-up wizards guide the user through the basic set-up functions. This helps prevent against omission of critical data inputs, and makes the software easier for less experienced users since the required data inputs are either highlighted or provided as default. Dialog boxes also use intuitive icons making them easily understandable.

VISUALLY CONTROLLED MESH REFINEMENT

To keep the total size of the model (total number of cells) controlled, a larger element size is usually used in the outer regions of a flow field while small mesh elements are applied near a model surface or in areas of high gradients. High gradient regions requiring increased mesh refinement include flow separations, jet flow mixing regions, and shock waves in compressible flows. Sometimes the locations (and size) of these complex flow phenomena are not intuitively obvious from just looking at the geometry. As the user’s experience he’ll be able to more appropriately determine which areas are defined as "details needed" or "details not needed" depending on the situation. SC/Tetra’s preprocessor offers helpful tools and easy interfaces to locally control the mesh-element density. These tools enable the user to precisely control the grid density anywhere within the model.

START TO END EXECUTION

In general, steps in a CFD analysis can be classified into two categories: man work for operations and setups, and computer work for calculations and processing. The tasks of these two categories are mixed one after another in a series of a process. However, if these can be re-grouped and organized into a larger set, you would first finish the man work part effectively and leave the rest to a PC. The "continuous execution" function of SC/Tetra has enabled this work separation.In addition, two or more jobs can be executed either successively or simultaneously; therefore, an efficient time usage can be attained by finishing all the man-work operations and settings during day time. Let the computers do their part during night time or weekends; then, you can check the results when you arrive at your office. SC/Tetra offers the efficiency in not only each application usage but also entire analysis procedure.