© fluent inc. 5/10/20152-1 fluent user services center introductory gambit notes gambit v2.1 jul...
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© Fluent Inc. 04/18/232-1
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Creating Geometry in GAMBIT
© Fluent Inc. 04/18/232-2
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Preliminaries-1 Objective:
Create and mesh the fluid region for flow problems and solid regions for heat transfer (and structural analysis for Fidap Users).
Typically accomplished by constructing and working with lower order entity objects and volume primitives.
Terminology: Vertex - a point Edge - a curve that is defined by at least 1 vertex (in the case of 1
vertex, the edge forms a loop) Face - a surface (not necessarily planar) bounded by at least 1 edge
(except for sphere and torus) Volume - a geometric solid (as in a solids model), also can be
thought of as an "air tight" set of bounding faces.
Lowest order entity
Highest order entity
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Preliminaries-2 Color Identification
Vertices and Edges are colored according to the highest order entity to which they are connected.
The coloring scheme is: Vertex (white) Edge (yellow) Face (light blue) Volume (green)
Undo/Redo: 10 levels of undo by default.
Undoes geometry, meshing, and zoning commands. Description window provides command to be undone
when mouse is passed over undo button. Left click to execute visible button operation. Right click to access options.
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
General Operations: Coordinate System
Coordinate systemCartesian, Cylindrical and Spherical systems
Using Offset/Angle or Vertices for location/orientation
"Active" coordinate system is default in all forms
Grid creation with "snapping" of vertices
-Recommended for simple geometries only
Creation of rulers
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
General Operations: Move/Copy Move/Copy
Operations: Translate:
(inputs are s)
Reflect:
Plane normal to vector
(x,y,z)
Angle
Vector
Vector
Rotate:
Scale:
Options: Connected geometry can also be Moved Mesh and/or Zone types can be copied linked or unlinked
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
General Operations: Vector Definition Form Vector Definition form
is used in: Rotate and Reflect (in Move/Copy) Sweep and Revolve (in Face/Volume
Create) Methods:
Coordinate system axis Two existing vertices An existing Edge Two points defined by coordinates Screen View
Magnitude option allows size of vector to be defined.
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
General Operations: Align
Align Align is an alternative to
Move - translate (+rotate).
It uses vertices on the start and final position to move the object
Method of increased alignmentwith the use of vertex-pairs
Connected geometry can be included
Rotation Plane alignmentTranslation++
++ ++++ + +
3 3
1 1
2 2
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
General Operations: Connect
Connect (Real) Vertices, Edges and Faces can be connected The operation eliminates all duplicate entities
and reconnects upper topology Only entities within the ACIS tolerance
will be connected Existing mesh will be preserved
Connect EdgesCopy +Translate
Two Edges One EdgeOne Face
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
General Operations: Disconnect
Disconnect (Real) Vertices, Edges and Faces can be
disconnected The operation recreates duplicate entities
and reconnects upper topology Several options exists
Disconnect
Two EdgesOne EdgeEdge + Vertices
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
General Operations: Delete
Delete
Select Lower Geometry (default)
Deletes Faces Deletes Lower Geometry:
Edges and Vertices
Deselect Lower Geometry Deletes Faces Does NOT delete Lower
Geometry: Edges and Vertices
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Example: Deleting Entities that belong to higher order Entities
The selected face can NOT be deleted because it is connected to a volume.
Correct: Delete Volume (deselect Lower Geometry)
Volume is deleted. Faces, Edges and Vertices are not deleted. Any of the six faces can be deleted
Incorrect: Attempt to delete Face (of a Volume)
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
General Operations: Misc. Summarize/Query/Total
Summary of vertex coordinates,lower topology, mesh information, element/node labels, etc.
Checks for valid ACIS geometry
Query: useful to associate geometrical objects with object names
Get total number of Entities
Modify Color/Label
Modify entity colors
Change entity label
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Geometry Creation ACIS - geometry engine ("kernel")
Provides tools for “bottom-up” creation by: Vertex: Add, Grid Snap, etc. Edge: Line, Arc, Ellipse, Fillet, B-spline, etc. Face: Wire Frame, Sweep, Net, etc. Volume: Wire Frame, Sweep, Face Stitch, etc.
Provides tools for “top-down” creation by Face Primitives: Rectangle, Circle, Ellipse Volume Primitives: Brick, Cylinder, Sphere, etc. Volume/Face Booleans: Unite, Subtract, Intersect Volume/Face Decompose: Split
Geometry creation typically involves use of all tools.
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Vertex Creation-1 Real Vertex creation
By coordinates Cartesian, cylindrical and spherical coordinate systems Also available in virtual geometry
On edge If the intention is to split the edge, the Edge-Split
form should be used instead
On face Useful to create edges on surface for a virtual split
In volumes Not frequently used
At edge-edge intersections Vertex is not connected to either edge Split edge with vertex for connectivity
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Vertex Creation-2
Import point data, File File format:
ICEM Input
Vertex Data Format is similar, curve information is not needed
npc nc
x1 y1 z1
x2 y2 z2
:
xn yn zn
Where: n = npc* nc is the total number of pointsnpc is the number of points per curvenc is the number of curvesxi yi zi are real or integer vertex coordinates
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Edge Creation-1 Real Edge creation
Straight line Multiple edges can be created by selecting
multiple vertices.
Arc, Circle Face create counterparts available Creation Methods
Three vertices on the edge Using Center and End-points Using Radius and Start/End Angles (Arc
Only)
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"Bottom Up": Edge Creation-2 Real Edge creation
Elliptical Arc Created by three vertices
Conic Arc Created by three vertices
+
+
+Major Vertex
On Edge VertexCenter Vertex
End Angle
Start Angle
+
+
+Shoulder Vertex
End Vertex
Start Vertex
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Edge Creation-3 Real Edge creation
Fillet Arc Creates a fillet out of a corner
NURBS Third-order by default Use tolerance for the approximate option
+
++Edge 1
Edge 2
Radius
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Edge Creation-4
Real Edge creationRevolve Vertex
Select one or more vertices to rotate Specify Angle Axis is defined using Vector Definition Panel Input Height for Spiral creation
Project Edge on Surface Limited to single edge
and face Direction defined in
Vector DefinitionPanel
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Face Creation-1 Real Face creation
Wire Frame Creates real and virtual faces All edges have to be connected into one loop Number of edges and order of picking are not important If all edges are co-planar — creation is always successful For non-coplanar edges:
The number of edges has to be 3 or 4 Edges cannot have the same tangent
at the connecting vertex
create real face
by wire frame
co-planar edges real face
+
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Face Creation-2 Real Face creation
Parallelogram defined by three vertices
Polygon Selection order is important. 5 or more vertices must be coplanar.
Vertex rows Tolerance input
Skin Topologically parallel edges Edges have to be picked in order Both ends of all edges can coincide
Net Topologically intersecting edges
+
+
+
++
+
+
+
+
+
+
++
+
+
+
+
++
+
+ +
++
+
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+
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++
+
+
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Face Creation with Revolve Real Face creation
Revolve (With or without mesh) Using an edge, an angle and a
revolving vector Use vectors for definition of the axis
of revolution Basic edge can coincide with axis
axis of revolution
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Face Creation with Sweep
Path
Perpendicular Twist: Angle = 120
Perpendicular Draft: Angle = - 30, 0, 30
Rigid
PathEdge
Real Face Creation: Sweep (with or without mesh) Rigid sweep
Edge translated along sweep path without being rotated Perpendicular sweep: Draft and Twist option
Angle edge makes with sweep path is maintained as edge swept along path
Be careful not to create degenerate faces Sweep path start tangent vector parallel to edge tangent
Edge
RigidPerpendicular Draft: Angle=0
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Face Primitives Face Primitives
Dimensions and Plane/Direction must be specified
Rectangles
Circles
Ellipses
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Volume Creation-1 Real Volume creation
Stitch Create volumes out of connected faces
If a few faces are missing, GAMBIT automatically finds the missing faces
Available in virtual geometry Order of picking not essential Voids not allowed
Revolve (With or without mesh) Using a face, a revolving vector and an
angle Use edges or vectors for definition of
the axis of revolution
ten connected faces one volume
axis of revolution
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Volume Creation-2 Real Volume creation
Wire Frame Create volumes from connected curves Number of edges and order of picking is not important Voids and seamless volumes and faces cannot be created Same limitation as face wire frame creation, for each face
36 connected edges one volume
© Fluent Inc. 04/18/232-27
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
"Bottom Up": Volume Creation with Sweep
Path
Perpendicular Twist: Angle = 60
Rigid
Real Volume Creation: Sweep (with or without mesh) Rigid sweep
Edge translated along sweep path without being rotated Perpendicular sweep: Draft and Twist option
Angle edge makes with sweep path is maintained as edge swept along path
Be careful not to create degenerate volumes Sweep path start tangent vector perpendicular to a face normal
Path
Face
Perpendicular Draft: Angle=0
Face
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Volume Primitives-1 Real Volume Primitives
Brick Width (X), Depth (Y) and Height (Z) The Width (X) value is used for Y and Z if
no other input is given. 10 different preset positions (each octant
plus center)
Cylinder and Frustum Height and two cross-sectional radii (3rd
radius for frustum) The Radius 1 value is used for remaining
radii if no other radius input is given. 9 different preset directions (three in each
axis)
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Volume Primitives-2 Real Volume Primitives
Prism and Pyramid Corresponding to input of cylinder and
frustum Number of sides 9 different preset directions (three in each
axis)
Sphere - only one radius
Torus Major and cross-sectional radii Three axis locations
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Boolean Operations: Unite Real Face/Volume Boolean Unites
The order of picking is not important (except for labeling) Retain - keeps copies of the entities
Unite Faces All faces must be coplanar or have
matching tangents.
Unite Volumes
AB A + B
AB A + B
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Boolean Operations: Subtract Real Face/Volume Boolean Subtract
The order of picking is important Retain - keeps copies of entities
Subtract Faces All faces have to be coplanar
Subtract Volumes
AB A - B
B - A
A - B B - A A
BA
B
Multiple entities can be enteredin second list box.
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Boolean Operations: Intersection
Real Face/Volume Boolean Intersect The order of picking is not important (except for labeling) Retain - keeps copies of entities. All entities must intersect each other.
Intersect Faces All faces have to be coplanar
Intersect Volumes
BA
BA
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The Split Operation: Employs the intersection of two geometric entities to divide one or both objects into two or more pieces.
Useful for decomposing complicated geometries into smaller, simpler ones. Edge Split
Split an edge into two or more edges Resulting edges are, by default, connected. Edges can be split with:
Point - specify U Value between 0 and 1 where edge will be split.
Use 0.5 to split edge in half. Vertex - must already be created. Edge
Must already be created Bi-directional option results in both edges
being split at point(s) of intersection.
Geometry Splitting- Edges
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Geometry Splitting- Faces
Real Face Boolean Split The order of picking is important Faces do not need to be coplanar
example: coplanar face splits
In general, for all splits (edges, faces, volumes): "Tool" entities are, by default, deleted after split is
performed Retain option prevents “Tool” entities from being
deleted. By default, resulting objects are connected.
Split A
with B
Split B with A
Two Faces
"Target Object"
"Tool"
Bidirectional split
Three Faces
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Geometry Splitting- Volumes Real Volume Boolean Split
The order of picking is important Volume/Volume splits
two volumes
Bidirectional Split
three volumes
Split A with B
B A
two volumes
Split B with A
two volumes Volume/Face splits
"Target" Object
"Tool"
B A
B A
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The appropriate operation to use can depend upon final geometry required.
Subtract Cut-away shows one volume results
Cannot mesh core region Flow/Heat Transfer in annular region only
Split Two connected volumes result
Cut-away shows that both annular and core regions can be meshed.
Flow/Heat Transfer possible in both regions Subtract + Retain "Tool" (inner cylinder)
Two disconnected volumes result, appears same as split Duplicate faces appear at interface
Non-conformal mesh can result Useful for multiple reference frame problem (Fluent)
Split vs. Subtract
Start with two disconnected
cylinders
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
The appropriate operation to use can depend upon the need to create additional surfaces for:
defining boundary conditions controlling meshing distribution
Bidirectional Split vs. Unite
Unite Unite
One volume results Cut-away shows no
interior faces
BiDirectional Split
Bidirectional split Three connected volumes result Cut-away shows multiple interior faces which can be used to:
define internal boundaries help control mesh distribution in volume
Total represented volume is the same
Start with two
disconnected cylinders
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Boolean Characteristics: Imprinting Uniting Connected Volumes Results in Imprinting
Unite A with B
A and C are connected cubes, B is a cylinder inside both
A C
Volume.1
Volume.2: face contains an imprint of the cylinder
B
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Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003
Volume Blends Real Volume Blends
Blend - create fillet/rounded edges Pick a volume Pick the edges that need a blend and
specify radius Pick vertex (if needed) and specify radius
using the Setback option Bulge option is not recommended for
hexahedral meshing
Bulge option
Setback option
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