S O F T W A R E   I N N O V A T I O N S

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
image  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
image  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
image  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
image  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
image   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
image   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

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