Description
Pointwise's structured solver for domains is a true "surface" solver, in that grid points are inserted directly on a specified geometrical shape (the database). The options in this frame are used to specify the manner in which that shape is maintained during solution.
The Shape pull down list contains the following options:
- Free: The shape is computed implicitly as a result of the triangulation method for the Cartesian coordinates (x,y,z). If the grid is constrained to the database and you run the solver with the free shape attribute, then the grid will no longer conform to the database. Free is the default shape attribute unless Pointwise has automatically applied either Parametric or Parametric Fit Triangulation when the domain was created. In that case the default shape attribute is database.
- Fixed: The solution of the elliptic PDEs is performed in a parametric space corresponding to the grid's original (u,v) coordinates. If the grid is constrained to a database, this method will not destroy the grid-database relationship. This method is generally used when the existing grid points lie on the intended shape but are not distributed in the desired manner and no database is available.
- Database: This method is used to have the grid conform to one or more database entities. For best results, the starting grid should already lie on the database entities which can be accomplished automatically when the grid is created or by projecting the domain onto the database later.
The Projection Method option determines how grid points are moved onto the database. There are two choices:
- Closest Point: This attribute tells Pointwise that the projection type is closest point and a projection vector is not required.
- Linear: This attribute tells Pointwise the projection type is linear. The projection direction can be set using the default projection direction or the Projection Orientation: Set button.
Note: The projection type selected for the Edit, Project command will be stored as an attribute of a domain so that when using Grid, Solve, the Projection Method will default to the same.
Once the Projection Method has been specified, it is time to define the orientation of such projection. To this end, you can use the options provided in the Projection Orientation section of the frame.
The Set button becomes enabled when the Projection Method is set to Linear and the Use Default checkbox (explained below) is unchecked. When this button is pressed, it indicates that the domain grid points will be projected onto the specified database surface along a fixed vector perpendicular to the Display window (screen-z)
The Use Default checkbox is used to indicate whether the default projection orientation should be used (option checked on) or not (option unchecked). Note that the default projection orientation is computed by averaging the grid's normal vector at each grid point.
In the Target Database Selction frame, Begin allows you to select the target projection entities from all those currently visible. After this button is pressed you can select database entities from either the List panel or Display window. The current set of target entities is already picked when the button is first pressed. The button remains depressed with the text End now displayed. Pressing End stops selection of projection database entities.
The Use Default button in this frame is used to indicate whether the domain grid points will be projected onto the default set of database entities or not. The default database entities are computed for each grid based on which entities are currently referenced by the domain's grid points, both on the interior and the domain's bounding connectors.