© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003 Creating Geometry in GAMBIT

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center 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.

© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003 General Operations: Coordinate System  Coordinate system Cartesian, 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

© Fluent Inc. 5/10/ Fluent User Services Center 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 Rotate: Scale:  Options: Connected geometry can also be Moved Mesh and/or Zone types can be copied linked or unlinked

© Fluent Inc. 5/10/ Fluent User Services Center 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.

© Fluent Inc. 5/10/ Fluent User Services Center 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 alignment with the use of vertex-pairs Connected geometry can be included RotationPlane alignmentTranslation

© Fluent Inc. 5/10/ Fluent User Services Center 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 Edges Copy +Translate Two Edges One Edge One Face

© Fluent Inc. 5/10/ Fluent User Services Center 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 Edges One Edge Edge + Vertices

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center 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)

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center 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.

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center 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 n pc n c x 1 y 1 z 1 x 2 y 2 z 2 : x n y n z n Where:n = n pc * n c is the total number of points n pc is the number of points per curve n c is the number of curves x i y i z i are real or integer vertex coordinates

© Fluent Inc. 5/10/ Fluent User Services Center 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 s Three vertices on the edge s Using Center and End-points s Using Radius and Start/End Angles (Arc Only)

© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003 "Bottom Up": Edge Creation-2  Real Edge creation Elliptical Arc Created by three vertices Conic Arc Created by three vertices Major Vertex On Edge Vertex Center Vertex End Angle Start Angle Shoulder Vertex End Vertex Start Vertex

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003 "Bottom Up": Edge Creation-4  Real Edge creation Revolve 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 Definition Panel

© Fluent Inc. 5/10/ Fluent User Services Center 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: s The number of edges has to be 3 or 4 s Edges cannot have the same tangent at the connecting vertex create real face by wire frame co-planar edges real face +

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center 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 Path Edge  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 Rigid Perpendicular Draft: Angle=0

© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003 Face Primitives  Face Primitives Dimensions and Plane/Direction must be specified Rectangles Circles Ellipses

© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003 "Bottom Up": Volume Creation-1  Real Volume creation Stitch Create volumes out of connected faces s 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

© Fluent Inc. 5/10/ Fluent User Services Center 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. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center 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)

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003 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 A B A + B A B

© Fluent Inc. 5/10/ Fluent User Services Center 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 A B A - B B - A A - BB - A A B A B Multiple entities can be entered in second list box.

© Fluent Inc. 5/10/ Fluent User Services Center 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 B A B A

© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003  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. s Use 0.5 to split edge in half. Vertex - must already be created. Edge s Must already be created s Bi-directional option results in both edges being split at point(s) of intersection. Geometry Splitting- Edges

© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003 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

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center Introductory GAMBIT Notes GAMBIT v2.1 Jul 2003  The appropriate operation to use can depend upon final geometry required. Subtract Cut-away shows one volume results s Cannot mesh core region s Flow/Heat Transfer in annular region only Split Two connected volumes result s Cut-away shows that both annular and core regions can be meshed. s 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 s Non-conformal mesh can result s Useful for multiple reference frame problem (Fluent) Split vs. Subtract Start with two disconnected cylinders

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center 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

© Fluent Inc. 5/10/ Fluent User Services Center 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