58:110 Computer-Aided Engineering Spring 2005

Grid Generation in GAMBIT

By Xiongbin Liu Department of Mechanical and industrial engineering

The University of IowaFebruary 2005

Introduction

• GAMBIT: a tool for mesh or grid generation for a CFD solver

• Two kinds of meshes:

(1) Structured mesh (rectangular grid)

(2) Unstructured mesh

(tetrahedrals (pyramid shape), prisms)

• Fluent: a CFD solver which can handle both kinds of

meshes

Launch Gambit or Fluent

• 1. mkdir xxx

• 2.  mkdir /var/tmp/name 

• 3.  cp ~/problem1/xxx    /var/tmp/name • 4.  cd /var/tmp/name

• 5. gambit

• 6. cp xxx  ~/problem1

• source /usr/ui/class/aux/fluent_setup.csh

• http://css.engineering.uiowa.edu/sware/unix_software.html#Fluent

GAMBIT graphic user Interface (8 Components)

main menu bar Operation Toolpad

Form field

Global Control Pad

DescriptionWindows

Transcript Windows

Command Box

Main Menu Bar

Three Data Files:Filename.jou (Journal, text format, a list of geometry, mesh, zone)Filename.trn (Transcript, text format, a log of messages displayed)Filename.dbs (database, binary format, geometry, mesh)

Mouse operation

Left-drag: rotate the model;

middle-drag: translate the model;

Right-drag: zoom the model in or out, rotate the view of the model about the center;

Shift-left-click: highlight the entity in the graphics wiondows and include in the current active pick list.

Global Control Pad

Global Control Pad

Geometry Mesh Zones Tools

Basic elements of Geometry

• Vertex

• Edge

• Face

• Volume (if 3d)

Mesh generation

Select mesh edges

Spacing (Interval Size, Interval count)

Ratio = 1 for Uniform Mesh Ratio <> 1 For Non Uniform mesh

Generate mesh on the face

Specify boundary Condition

Export mesh data

File-Export-Mesh-Export

Practice: Flow passing around half a cylinder (2d)

10

5

2

5 (0,0)