CREATING THE GEOMETRY
© 1998–2007 Fluent, Inc. All rights reserved. 2-1
2. CREATING THE GEOMETRY
When you click the Geometry command button on the Operation toolpad,
GAMBIT opens the Geometry subpad. The Geometry subpad contains com-
mand buttons that allow you to create, move, copy, modify, summarize, and
delete vertices, edges, faces, and volumes. The Geometry subpad also contains
a command button that allows you to perform operations involving groups of
topological entities.
The symbols associated with each of the Geometry subpad command sets are
as follows.
Symbol Command Set
Vertex
Edge
Face
Volume
Group
The following sections of this chapter describe general operations related to
building a GAMBIT model as well as the commands necessary to create and
modify the topological entities listed above.
General Operations CREATING THE GEOMETRY
2-2 © 1998–2007 Fluent, Inc. All rights reserved.
2.1 General Operations
2.1.1 Labeling Entities
Each of the GAMBIT modeling forms that allow you to create a new entity
also allows you to specify a label for the entity. For example, if you create a
vertex using the Create Real Vertex form (Figure 2-1), you can specify a label
for the vertex by entering a name in the Label text box at the bottom of the
form.
Figure 2-1: Example Create Real Vertex form
If you create an entity or coordinate system without specifying a label,
GAMBIT automatically assigns a label to the entity. The automatically
assigned label consists of a name representing the entity type followed by a
decimal point and an integer—for example, volume.6. Automatically assigned
labels for virtual, faceted, and CAD entities are preceded by the characters
“v_”, “f_”, and “c_”, respectively—for example, v_volume.6, f_edge.12, and
c_face.9.
NOTE: For a description of the differences between real, virtual, faceted, and
CAD entities, see the Appendix of this guide.
CREATING THE GEOMETRY General Operations
© 1998–2007 Fluent, Inc. All rights reserved. 2-3
GAMBIT uses the following names for automatically labeled entities and
coordinate systems.
Item Real Virtual Faceted CAD
Vertex
vertex v_vertex f_vertex c_vertex
Edge
edge v_edge f_edge c_edge
Face
face v_face f_face c_face
Volume
volume v_volume f_volume c_volume
Group
group
N/A N/A N/A
Coordinate System
c_sys
N/A N/A N/A
The integer that GAMBIT assigns to automatically labeled entity names is
equal to n+1, where n is the highest integer associated with any currently
existing entity of the same type. The value of the assigned integer is independ-
ent of whether or not the entity is real or virtual.
The following examples summarize the general rules that GAMBIT uses for
automatically labeling new entities.
• If you create a real vertex in a model that already contains vertices
labeled vertex.1, vertex.2, and vertex.3, the new vertex is named vertex.4.
• If you create real vertices vertex.1, vertex.2, and vertex.3, then delete
vertex.3—so that the model only contains vertex.1 and vertex.2—the
next automatically labeled real vertex is named vertex.3.
• If you create real vertices vertex.1, vertex.2, and vertex.3, then delete
vertex.2—so that the model only contains vertex.1 and vertex.3, the next
automatically labeled real vertex is named vertex.4.
General Operations CREATING THE GEOMETRY
2-4 © 1998–2007 Fluent, Inc. All rights reserved.
2.1.2 Specifying Entities
Specifying Individual Entities
Many of the modeling forms require you to specify individual entities—such
as vertices, edges, or faces—to which to apply the operations specified on the
form. When a form requires you to specify one or more individual entities, it
contains a list box titled with the entity type. For example, the Create Real
Vertex form (see Figure 2-1) requires you to specify the coordinate system
with respect to which the vertex is to be positioned; therefore, it contains a list
box, titled Coordinate Sys.
Unless otherwise noted, you can specify an individual entity in one of three
ways:
• Input the name of the entity in the list box, and press Enter.
• Click the pick-list button at the right side of the list box, and select the
entity by means of the pick-list form.
• Pick the entity from the model as displayed in the graphics window.
Specifying Multiple Entities
On some forms, GAMBIT provides a list box that allows you to specify more
than one entity for a single operation. For example, the list box on the
Connect Faces form allows you to specify multiple faces to be connected. For
list boxes that allow the specification of multiple entities, you can specify the
entities in one of three ways:
• Input the first entity name, press Enter; clear the list box, input the
next entity name, press Enter again; and repeat the input sequence for
each entity.
• Click the pick-list button located at the right side of the list box, and
select the entities by means of the pick-list form.
• In the graphics window, Shift-right-click on a vertex or edge associ-
ated with each entity to be specified (picked) for the operation.
(NOTE
: To select entities that share a common lower-topology entity,
you can pick the lower-topology entity multiple times. For example, to
pick three faces that share a common edge, you can pick the common
edge three times.)
CREATING THE GEOMETRY General Operations
© 1998–2007 Fluent, Inc. All rights reserved. 2-5
2.1.3 Working with Coordinate Systems
Some of the GAMBIT modeling forms require you to specify a location in
space relative to a specified coordinate system. For example, the Create Real
Vertex form shown in Figure 2-1 requires you to specify the three coordinates
describing the point at which the vertex is to be created.
You can specify point coordinates with respect to either a global or local coor-
dinate system. GAMBIT’s global coordinate system is named c_sys.1, and it
cannot be deleted. As a result, it is always available for the specification of
coordinates. To specify the coordinates of a point relative to a local coordinate
system, you must first create the local system using the procedures outlined in
Section 5.1.2 of this guide.
To specify the location of a point, you must specify the following information:
• The reference coordinate system (global or local)
• Three coordinate parameters that describe the point relative to the
specified reference system
Specifying Reference Coordinate Systems
You can specify the reference coordinate system in one of three ways:
• Input the name of the coordinate system in the Coordinate Sys list box.
• Click the pick-list button located at the right side of the Coordinate Sys
list box and select the system from the coordinate-system pick list.
• Pick the coordinate system (on one of its axes) in the graphics
window.
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