introduction to gambit

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Introductory GAMBIT Notes GAMBIT v2.0 Jan 2002

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Introduction to GAMBIT

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Agenda Day 1

Introduction

Tutorial 1: Creating and Meshing Basic Geometry

Creating Geometry in Gambit

Tutorial 2: Geometry Creation Exercises

Lunch

Edge/Face Meshing and Mesh Quality

Tutorial 3: Edge and Face Meshing Exercises

Volume Meshing and the Sizing Function

Tutorial 4: Volume Meshing and Sizing Function Exercises

Volume Decomposition Examples

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Agenda Day 2

Tutorial 5: Volume Decomposition Exercises

Mesh Control through Boundary Layers and Face Vertex Types

Tutorial 6: Vertex Types

CAD/CAE Import and Geometry Cleanup

Tutorial 7 or 8: Geometry Import Exercise

Lunch

Tutorial 7 or 8: Continued orOptional: G/Turbo (Indicate Interest)

Work on your own Projector Tutorial 9: Hex meshing the Flow Probe

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What is GAMBIT?

A single, integrated preprocessor for CFD analysis: Geometry construction and import

Using ACIS solid modeling capabilities Using STEP, Parasolid, IGES, etc. import

Cleanup and modification of imported data Mesh generation for all Fluent solvers (including FIDAP and POLYFLOW)

Structured and Unstructured hexahedral, tetrahedral, pyramid, and prisms. Mesh quality examination Boundary zone assignment

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Operation General sequence of operations

Initial setup Solver selection, Mesh size, Defaults, etc.

Geometry Creation (ACIS, STEP, Parasolid, IGES or Mesh import) Create full geometry Decompose into mesh-able sections

Meshing Local meshing: Edge and Boundary layers Global meshing: Face and/or Volume

Mesh examination Zone assignment

Continuum and Boundary attachment Mesh export

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Files (1)

GAMBIT directory and files When GAMBIT starts up, it creates a directory called GAMBIT.#

# = the process number It also creates a “lock” file, ident.lok, in the working directory ident.lok prevents any user from starting up another session using the

same identifier in the same directory. If the code crashes, this file needs to be manually removed.

Three files are created inside this directory ident.dbs =

jou =

trn =

the database. All information will be saved in this file. This file is NOT retrievable upon a crash

the journal file. This file is directly accessible

from the Run journal form

the transcript file. Output from GAMBIT

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Files (2)

GAMBIT directory and files GAMBIT permanently saves these files to your working directory as

ident.dbs, ident.jou and ident.trn anytime you issue a “Save” option (equivalent to any standard word processor)

Upon Save, earlier versions of ident.dbs and ident.trn will be overwritten, while new commands are appended to the file ident.jou

Upon successful exit of GAMBIT: The directory GAMBIT.# is removed The lock-file ident.lok is deleted

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Startup: DEMO

Start gambit with “gambit filename”

NT Users must start Gambit this way from a command prompt.

Example: Start Gambit in directory “projects”

> gambit airfoil

Before save

After save

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Journal Files

Journal File: Executable list of Gambit commands

Created automatically by Gambit from GUI and TUI. Can be edited or created externally with text editor.

Journals are small - easy to transfer, e-mail, store Uses:

Can be parameterized, comments can be added Easy recovery from a crash or power loss edit existing commands to create new ones

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Running Journal Files Journal files can be processed in two ways:

Batch mode (Run) All commands processed without interruption. “read pause” command will force interrupt with

resume option appearing. Interactive mode (Edit/Run)

Includes text editor for easy modifications Mark lines in process field

to activate for processing. Editable text field. Right click text field

for more options. Auto or Step through

activated process lines.

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Journal File: Parametric Modeling Parameters (incl. arrays), control-blocks, do-loops, arithmetic functions,

etc., can be used in the Journal File for simplifying parametric studies.

Comment lines

Parameter names begin with $

Commands are not case sensitive

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GUIMain Menu bar

Global Control

Operation toolpad

Command line Description window

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Operation Tool Pads

VertexEdgeFace VolumeGroup

Boundary LayerEdgeFace VolumeGroup

Boundary Types Boundary EntityContinuum Types Continuum Entity

Coordinate SystemsSizing FunctionG/TurboUser-Defined Tools

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File Menu (1)

New, Open, Save, Save As and Exit Standard form of database operations

Print Graphics Prints graphics to printer or to file PostScript, BMP, TIF, etc.

Run Journal / Clean Journal Screen editor/command processor for journal files Command processing:

Partial or global selection/de-selection Automatic or stepwise processing

Ability to load the current journal File browser Clean Journal removes unnecessary tags, undo’s, etc.

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File Menu (2) View File

View of the current output,ident.trn, the transcript file

Ability to view other files as well Import

ACIS, Parasolid - IGES, STEP ICEM Input, Vertex Data CAD - Pro/E, Optegra Visualizer, I-DEAS FTL Mesh - mesh and faceted geometry files.

Export ACIS, Parasolid IGES, STEP Mesh - Export your mesh for your Solver.

2D option guarantees 2D mesh

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Edit Menu (1)

Edit Title Title will be included on any printed graphics

Edit File Ability to launch an editor within GAMBIT

Edit Parameters Ability to define, modify and list parameters

parameters: $numeric = 10,

arrays: $array(3,4) = 5 Parameters and arrays can also be directly defined in

the journal file using an editor (preferred option)

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Edit Menu (2)

Edit Defaults Modify a large range of defaults that effect:

User Environment Meshing Characteristics Geometry

Ability to load, modify and save a new set of defaults in $HOME/GAMBIT.ini which is loaded automatically at startup.

Undo/Redo Ten levels of undo/redo (default) Reducing number of levels also reduces memory

requirements.

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Solver Menu

The Solver selection will have an impact on the following input forms:

Available meshing algorithms Available element types Continuum types Boundary types Export mesh file

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Graphical User Interface Command:

Input of (non-GUI) commands, e.g., reset: deletes all mesh and geometry in the current model reset mesh: deletes mesh, keeps geometry

Description Gives a short description of all global function buttons and screen areas

Transcript Output from GAMBIT is printed here as well as in ident.trn Transcript window can be expanded using arrow button in top right corner

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Global Control (1)

Scale-to-Fit Pivot anchor forviewmanipulation

Four splitFour view

Light sourceSpecial LabelsAnnotate

Undo/Redo

Orient ModelJournal View

Modify (on/off) Label Visibility Rendering Show mesh Silhouette

Wire frameShadeHidden Line

Color coding Entity type Connectivity

Examine Mesh

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Global Control (2) Scale-to-fit resizes the model to fit the screen Orient Model - major axes , isometric and:

Reverse

Previous

Journal view Select Pivot - around which the model rotates, zooms

Body center

Mouse position Model display attributes

Turn on/off visibility, label, silhouette, mesh and hidden line on all or selected geometrical entities

Preset configuration of the graphics window4-view and 4-split

Options to return to any single view

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Global Control (3) The Window Attributes form

Modify the following attributes (defaults given) Render Wireframe on ; shaded and hidden off Mesh Volume - off Silhouette All on Label All off Visibility All on

Two ways of picking entities “All” - All entities are picked (Default) “Pick” - Individual picking including

the use of pick lists

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Global (4)

Render Model - Wireframe , Shaded , Hidden Modify Light/Label type

Change light source orientation and properties

Additional information on the entity label

Insert arrows and text for graphic presentations Color Mode

Color by entity

Color by connectivity Undo/Redo

Examine Mesh Display different element types by quality, plane cuts, etc.

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Forms (1) Form - components

List box - (picking) active (yellow) - ready to pick inactive (white) - click to activate

Radio buttons mutually exclusive options

Option button Option menu

Text box Click-to-focus

Check box non-mutually exclusive options

Command buttons

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Forms (2)

Text box

Field for input of data, expressions, parameters The cursor is blinking if active

To activate - left click in the text box (click-to-focus) Forms with several text boxes

The order of input is not important Use “tab” to go to the next text box Use left click (click-to-focus) to go to any text box

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Forms (3)

List box Highlighted in yellow if active

To activate - left click in the list box Tells you the name of the latest picked item

The item is highlighted in red on the screen All previously picked items are pink

Individual pick lists for each list box Forms with several list boxes:

Depending on the form, the order of picking may be important Use Shift right-click to go to the next list box Use left click (in the list box) to go to any list box

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Forms (4) Pick Lists

Open the Pick List by clicking on the arrow

The “Available” list is sorted in the order of picking Pick List functionality:

Pick or Un-pick, Selected or All entities by highlight in left column and by clicking on the arrows

Highlighted “picked” entities will appear red on the screen edge.32, edge.33

Non-highlighted “picked” entities will appear pink edge.26, edge.28

Right-click in lists area provides additional options Filter can be used to control which objects are picked.

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Mouse Operations (1)Left Middle Right

Drag x-y rotation Translation Zoom/ z-rotation

Shift +Click

Pick Next Accept/Next picker

DoubleClick

Previous View Save view to journal

Ctrl Drag zoom Stretch zoom Click points to grid

You can toggle between picking with or without “Shift”:Keep right mouse button down while doing a “left-click”The cursor now changes to another symbolNow, Pick/Next/Accept do not need a “Shift”The Rotation/Translation/Zoom now needs a “Shift”

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Mouse Operations (2) The picking philosophy: Left - Middle - Right

Shift-Left: initial pick Alternative: click and hold, drag diagonally to pick several items at the same

time - “window picking” The latest pick is highlighted in red, previously picked items are highlighted

in pink Shift-Middle: modify pick

The middle pick will behave differently depending on the mouse location: Same: Cycle to the next available object within picking

tolerance New: Replace last pick with new pick at new location Bad: A Shift-Middle pick on “nothing” is equivalent to

“Un-select last pick” Shift-Right: Apply or go to the next list box

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