Preferences |
Menu: Utilities->Preferences...
Toolbar:
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Preferences |
Note: There are many settings in GiD that have a predefined value, but that can be modified by the user. They can be accessed in one of two ways. Firstly, by opening the Preferences window from the Utilities pull-down menu, and secondly via the Variables command in the Utilities section of the Right buttons menu (the latter is also available in the Contextual mouse menu). Almost all the preferences variables are present in the Preferences window, but some advanced ones are only available in Variables command.
In the following section the different options available in the Preferences window are shown and their different settings explained.
Usually variables are graphically set trough the preferences window, but some unusual variables must be set from the lower command line, with this command:
Mescape Utilities Variables <varname> <varvalue>
if <varname> is not specified then the mouse contextual menu (see Mouse operations ) will show the list of available variables.
General |
The first group of Preferences are general options, and are used to set the different ways of working with GiD.
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- Always: If trying to create a new point in the vicinity of an existing one, the new point is always created.
- Ask: If trying to create a new point in the vicinity of an existing one, GiD asks whether to make use of the existing point or create a new one.
- Never: Only allows existing points to be selected. You can also change this when in point creation mode by setting No join until all points are entered.
Variable: CreateAlwaysNewPoint. Respective values: 1,0,-2. Default is 0 (Ask).
Graphical |
The second group of preferences are graphical options, and are used to set different ways of visualizing the model. They do not change the geometry or the model information.
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- None: Surfaces are not drawn.
- Boundary lines: One magenta line is drawn for every contour line. This set of lines has a small offset towards the interior of the surface.
- Isoparametric lines: Two yellow lines are drawn for every NURBS surface, one for u=0.5 and one for v=0.5.
- Both: Draws both Boundary lines and Isoparametric lines.
Variable: DrawSurfaceMode. Default is 1 (Boundary lines).
- No: If this option is set, quadratic elements are drawn as if they were linear.
- As lines: If this option is set, elements are drawn taking into account all quadratic nodes, but edges are drawn using straight lines between nodes.
- As curves: If this option is set, elements are drawn taking into account all quadratic nodes, and edges are represented using quadratic curves. This option is more realistic, but it may make some visualization aspects slower when dealing with large models.
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If this option is set various further options are available, though these only apply when rotating.
- Points, lines, surfaces, volumes: This determines whether the entities will be drawn when rotating. Variables: the same. Values: 0,1. Default is 0 (No).
- Always Geometry: With this option set, when you view and rotate the mesh, the geometry is drawn instead. Variable: UseAlwaysGeom. Values: 0,1. Default is 0 (No).
- Draw graphic objects: If this option is not set, when rotating the geometry, some graphical and temporal objects like normals or materials or conditions symbols are not drawn. Variable: DrawGraphicObjects. Values: 0,1. Default is 1 (Yes).
- Curve precision: This is the same as the general item Curve precision, but only applies when rotating. Variable: CurvePrecision. Values: 1.0 to 0.0 from best to worst. Default is 0.8
Meshing |
The third group of preferences are meshing options.
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- Linear: linear elements are made.
- Quadratic: the elements will be quadratic, with a node in the middle of each edge:
Linear: 3 nodes.
Triangle: 6 nodes.
Quadrilateral: 8 nodes.
Tetrahedra: 10 nodes.
Hexahedra: 20 nodes.
Prisms: 15 nodes.
- Quadratic9: option is similar to Quadratic, but will generate 9-noded quadrilaterals and 27-noded hexahedra (an extra node in the middle of the element).
The different conectivities can be seen at Element type .
GiD can use three kinds of surface mesher.
- Rfast meshes are the most efficient in speed and reliability. With deformed surfaces they can give distorted elements.
- Rsurf meshes are generated directly in the space. Quality is better but it is slower and can fail for distorted surfaces.
- Rjump meshes are generated directly in the space, and contact lines between surfaces which are almost tangent (less than 10 degrees between tangent vectors) are skipped when meshing. Contact points between almost tangent lines (less than 10 degrees between tangent vectors) are skipped too. With this surface mesher, you can generate meshes with fewer elements than other meshers because it is less dependent on the dimensions of geometrical surfaces. However, it is slower and can fail for distorted surface patches.
If any entity has Skip or NoSkip Mesh Criteria (see Mesh criteria ), the surfaces involved are meshed with the Rjump mesher, even if another mesher is set in this window. These mesh generators are based on the advancing front generation mesh technique in order to improve speed and portability. Variable: SurfaceMesher. Values: 0 (Rfast), 1 (Rsurf) and 4 (Rjump). Default is 0 (Rfast).Note: GiD can try another mesher internally when one of them fails to generate the mesh for one surface.
GiD can use two kinds of volume mesher:
- Advancing front: The unstructured volume mesher is based on the advancing front technique.
- Delaunay: The unstructured volume mesher is based on the Delaunay algorithm. It isn't constrained.
- Isosurface Stuffing: The unstructured volume mesher aplies the patterns of isosurface stuffing on a modified cartesian mesh of the model.
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- Stretching function: this variable set the stretching function which controls the height of each layer of boundary layer mesh. Options are the next ones, where 'h_i' is the height at level 'i' and 'r' is the grow factor:
- Function 1 (Geometric): This function is the geometric progression, and its expression is: h_i = h_0*(r^0+r^1+r^2+···+r^(i-1)
- Function 2 (Exponential): This function the exponential progression, and its expression is: h_i = exp(r*i + ln(h_0)).
- Function 3: This function is represented by: h_i = h_0 * (1 + i*(1+r*(1+r)*i))) . This function typically grows faster than the Geometric one.
Variable: BoundaryLayer(GrowLaw). Values: 0 (Function 1), 1 (Function 2) and 2 (Function 3). Default is 0 (Function 1).
- Grow Factor: This variable controls whether the stretching function grows slower (smaller values) or faster (bigger values). When Function 1 is used, grow factor must be greater than 1.0, and when Function 2 or 3 are used, grow factor must be a positive number. Variable: BoundaryLayer(GrowFactor). Value: positive real number. Default is 2.0.
The red line below these options shows schematically the difference of heigt of the different layers of boundary layer mesh.
- Boundary layer mesh in separated Layer: if this preference is set, the mesh elements which own to a boundary layer mesh will own to separated layers. The name of these layers will be the same as the Layer name of the geometrical entity where elements are, but with the prefix 'BLM_'. Variable: BoundaryLayer(MeshInSpecificLayer). Values: 0,1. Default is 0.
- Normal: only the standard smoothing is performed.
- HighAngle: an additional smoothing with angle criteria is performed.
- HighGeom: an additional smoothing with chordal error criteria is performed.
Variable: HighQualitySmoothing. Values: 0 (Normal), 1 (HighAngle) and 2 (HighGeom). Default is 1 (HighAngle).
Variable: ChordalError(ApplyChordalErrorToModel) (values 0,1), ChordalError(RelativeChordalError) (percentage, positive value), ChordalError(MaxChordalError) (positive value: it is a distance) and
ChordalError(MinElemSize) (positive value: it is a distance). Defaults are 0, 0.0, 0.0 and 0.0 (no chordal error criteria applied).
Algorithm:
1 = Optimization radius: iterative, optimizes distances and positions for minimum porosity.
(ref:Carlos Labra, Eugenio Oñate. High-density sphere packing for discrete element method simulations, Communications in Numerical Methods in Engineering 2009)
2 = Predefined porosity: iterative with fixed radius .Experimental.
3 = Radius expansion : iterative, corrects positions and increases radius.
4 = Optimization radius fast: it's 'Optimization radius' with less precision. (Experimental)
5 = Explicit: iterative, radius defined with porosity and optimizes positions.(Experimental)
Max. iterations: Maximum number of iterations for the choosed algorithm.
Advanced preferences:
Main:
MaxIterLocal: Number of iterations for filters.
Tolerance: Tolerance of distance function to terminate the process.
MinRadius: minimum radius Factor ( Minimum radius = MinRadius*UserRadius(size of element/2) ).
MaxRadius: maximum radius Factor (Maximum radius = MaxRadius*UserRadius(size of element/2) ).
DeltaPosition: perturbation of initial position factor ( Maximum perturbation = DeltaPosition*UserSize ).
DeltaRadius: Randomness of initial radius.( Minimum radius = (1-DeltaRadius)*UserRadius; Maximum radius = (1+DeltaRadius)*UserRadius] ).
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2D: delta position: 0.6; delta radius:0.6
3D: delta position: 0.4; delta radius:0.4
Preprocess: initial generation of spheres with porosity.
Porosity: Value of porosity for preprocess.
Postprocess: correction of final positions.Experimental.
Overlaps: checked permits overlaping between spheres. If not checked corrects radius of the sphere.
Filters:
Filter: Number of global iterations before activate sphere size filter.
Search: Number of gloabal iterations before activate the search of new overlapings between spheres.
SearchType: Type of search: ( 1=SpatialSearch(Tree-based) 2:WeightedDelaunyRemeshing )
ContactFactor: Sphere Neighborhood factor distance( Vecinas si : Distance(sphere1,sphere2) < ContactFactor*(sphere1.Radius+sphere2.Radius) )
NeighborFactor: Penalty factor between overlaped spheres (in optimization algorithm must be 1.0)
FacetFactor: Penalty factor between overlaped sphere wiht a surface (in optimization algorithm must be 1.0).
OverlapFactor: Factor to eliminate sphere with overlaps ( delete sphere if maximum Overlap > OverlapFactor * Sphere radius )
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Exchange |
The fourth group of preferences are geometry exchange (import and export) options.
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Import options:
Variable: AutoCollapseAfterImport. Default is active (1).
Variable: ImportTolerance. Default is 0.001.
- Ignoring Layers: Entities are also collapsed if they belong to different layers.
- Each layer separately: Entities in different layers are not collapsed. (Entities belonging to frozen layers are never considered.)
Variable: CollapseIgnoringLayers. Value: 0 (Each layer separately), 1 (Ignoring Layers). Default is 1 (Ignoring Layers).
Variable: IGESCurveOnSurfaceFrom3D. Value: 0 (space parameter definition), 1 (3D space definition). Default is 1 (3D space definition).
Variable: IGESCreateAllInLayerToUse. Value: 0 (IGES entities created in the file layers), 1 (IGES entities created in the current layer to use).
Export options:
Some CADs are not able to read the IGES B-Rep style and then can be interesting to use the alternative style.
Variable: IGESSolidsManifoldBRep. Value: 0 (no B-Rep output style), 1 (B-Rep output stype). Default is 1 (B-Rep output style).
Fonts |
The fifth group of preferences deals with the fonts used inside GiD.
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Format |
The sixth group of preferences deals with numerical formats used inside GiD.
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Grid |
The seventh group of preferences contains grid options (see Grid ).
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Variable: Grid(DrawLabels). Value: 0,1. Default is 0 (no show labels)