With GEMS, You Can Discover

in Geometry Modeling and Mesh Generation

GEMS is an object-oriented interactive geometry modeling and 2D/3D multiblock structured mesh generation system, designed as a preprocessor for solving complex flow simulation problems in Computational Fluid Dynamics (CFD) and related fields.

  • A New Generation of Software

    • A state-of-the-art software based on OOP and C++
    • Integrated geometry modeling and mesh generation tools
    • Multiblock structured grid generation options for surface and volume grids
    • Automatic grid generation
    • Intelligent topology definition by Case-Based Reasoning/Learning
    • Storage and recovery of the mesh generation process at any stage
    • Context sensitive help

    Figure: Definition of surface geometry by cross sectional cubic spline curves.

  • Geometry Modeling

    • Built in CAD options to create and edit grid boundary curves and surfaces
    • Supported curves : Arc, Line, Polyline, B-Spline, Cubic Spline, NURBS
    • Surface creation by mapping or interpolation
    • Surface intersection curves and surfaces of revolution
    • Reading external CAD data (sectional or wire frame) in IGES format
    • Specific curve and surface generation and editing options

    Figure: Definition of surface geometry by a number of patches (wireframe).

  • Grid Generation

    • Algebraic and elliptic (multigrid or SLOR) grid generation options
    • Translating, rotating or sweeping a face to create volume grids
    • Interactive control of boundary grid point distribution and orthogonality
    • Definition of various boundary conditions by surface patches
    • Interactive definition of topology, connectivity and boundary conditions
    • Surface and volume grid cell quality checks
    • Displaying and saving coarse levels for multigrid
    • Rendering, hidden line removal and color map representation
    • Overlapping grid cell display

    Figure: Surface grids on the FLYER prototype (courtesy of ERG Corp., Ankara)

  • Automatic Grid Generation

    • Macro (script) files to record modeling and generation steps interactively
    • Replaying macro files partially or completely to perform repeated tasks

    Figure: A six-block H-type grid for the coolant passages of a turbine blade.

  • Intelligent Topology Definition

    • Learning past experiences by Case Based Reasoning / Learning (CBR / CBL)

    • User preferences and user evaluation in storing and recovering grid topology

    • Case retrieval
    - by electing a previous topology or
    - by case suggestion utilizing the fitness metric

    • Constraint satisfaction based on
    - desired number of grid points,
    - grid cell quality,
    - multigrid levels and
    - flow solution method

    Figure: Selected block surfaces in an industrial combustion chamber geometry.

  • Development History

    • Originally developed by Dr. Cem Dener in June 1993

    • Supported by the Technology Development Fund of Turkey (TTGV)

    • TTGV-069 project to extend the capabilities of GEMS (Oct `93 - Dec `94))
    - Automatic Grid Generation (AGG) developed by Ms. Esin Koc
    - Intelligent Topology Definition (ITD) developed by Mr. Izzet Sirin

    Figure: Surface scrolling and surface rendering on space shuttle configuration.

  • Operating Platform

    • GEMS 3.3 : Silicon Graphics with IRIX

    • Requirements :
    - Min. 32 MB RAM
    - Min. 50 MB free space on hard disk
    - 1280x1024 pixel resolution display

We value professionalism, customer-oriented approach, planning & organization,
teamwork, continuous learning and sharing information