Noman Gambit

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What is GAMBIT?

A single, integrated preprocessor for CFD analysis:

Mesh generation for all Fluent solvers (including FIDAP and POLYFLOW) Structured and Unstructured hexahedral, tetrahedral, pyramid and prisms. Geometry construction and import Using ACIS solid modeling capabilities Using STEP, Para solid, IGES, etc. import Cleanup and modification of imported data Mesh quality examination

Boundary zone assignment

Introduction to GAMBIT:

Here we use Gambit software for generating meshes. In essence the mesh consists of a

discretization of the fluid domain into small control volumes called elements. For a better

simulation, the mesh must follow a given quality criteria, use the most suitable surface (triangles,

quads, etc.) and volume (tetrahedral, hexahedral, prism, pyramids, etc.) elements. To start

Gambit, make a double click on the icon Gambit 2.2.30. It opens a window where we have to

choose the working directory and select run (Run).


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Files:

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

Three files are created inside this directory ident.dbs = the database. All information will be saved in this file. This file is NOT

retrievable upon a crash

jou = the journal file. This file is directly accessible from the Run journal form trn = the transcript file. Output from GAMBIT

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


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Upon successful exit of GAMBIT:

The directory GAMBIT.# is removed The lock-file ident.lok is deleted

GUI Components:

GAMBIT allows you to construct and mesh models by means of its graphical user interface

(GUI), which is designed to be mouse-driven. The GAMBIT GUI consists of eight components,

each of which serves a separate purpose with respect to the creating and meshing of a model. The

following sections briefly describe the GUI components.


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Graphics Window:

The graphics window is the region of the GUI in which the model is displayed. It is located in

the upper left portion of the GUI and occupies most of the screen in the default layout. GAMBIT

Users Guide presents a more detailed description of the graphics window.

Main Menu Bar:

The main menu bar is located at the top of the GUI, directly above the graphics window. It

contains four menu items. Each of the items is associated with its own menu of commands that

allow you to perform various GAMBIT operations. To open the menu associated with any item,

left-click the item name (for example, File).GAMBIT Users Guide presents detailed

descriptions of the menu items, as well as the commands available on each associated menu.

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

Operation Tool Pad:

The Operation tool pad is located in the upper right portion of the GUI. It consists of a field of

command buttons, each of which performs a specific function associated with the process of

creating and meshing a model. Within the Operation tool pad, command buttons are grouped

according to their hierarchy and purpose in the overall scheme of creating and meshing the

model. The topmost group constitutes the main pad. All other command button groups constitute

sub pads.


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Sub Pads:

When you click a main-pad command button, GAMBIT opens an associated sub pad. For

example, if you click the GEOMETRY command button on the main pad, GAMBIT open the

Geometry sub pad. Each sub pad contains command buttons that perform operations related tothe overall purpose of the sub pad. For example, the Geometry sub pad contains command

buttons that allow you to perform operations related to the creation and refinement of model

geometry. Some of the command buttons located on sub pads open related sub pads of their own.

For example, when you click the VOLUME command button on the Geometry sub pad,

GAMBIT opens the Geometry/Volume sub pad. Each command button on the

Geometry/Volume sub pad is associated with a specification form that allows you to specify

parameters related to the function indicated on the button.

Operation:

In the upper right corner we find the icons corresponding to the main four operations (Operation)

that we may carry out within Gambit: Geometry, Mesh, Zones (determine boundary conditions)

and Volumes (from left to right).

Main Operations Icon:.Each one of these main operations contains a subgroup of icons that allow us to perform several

tasks. For example, by clicking on the main geometry icon, a new window appears, where we

can carry out operations with vertexes, edges, faces, volumes and groups.


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Global Control:

Form:

Text Box:

Field for input of data, expressions, parameters


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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

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 i.e.edge.32, edge.33 Non- highlighted picked entities will appear pink i.e. 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:

Problem Description:The problem to be considered is schematically in fig. We consider flow across a cylinder and

look at the wake behind the cylinder.


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Steps involve in making the above configuration:

First, I have made the circle by making the vertexes. And for that I picked the method like circle

with center with two vertices. The diameter of the circle is 1cm, as shown in figure. And for that

I have marked two vertices.


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Secondly, I have made the rectangular domain. And for that I have marked four vertices. And by

using line command I have made the lines to form the rectangle.

After that I have the face to the rectangular domain, by picking the command Operation >

Geometry > Face . Without making face we cannot provide the nodes to the domain.


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In the next step I have provided the nodes for making the mesh. I gave 150 nodes throughout the

whole rectangle. You can provide the nodes on your own will by choosing the command like

interval count.


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In the last step, I used the mesh command to mesh the whole rectangle, as you can see in belowfigure. For completing this step, followings commands were used Operation > Mesh > Face .And Finally I got the results of the object and analyze the worst element and aspect ratio.Finally got


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Noman Gambit

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