Description

Spacing refers to the distance between the boundary (edge for domains and face for blocks) grid points and the first layer of grid points inward from the boundary.

Spacing Controls
Use the controls provided in the Spacing Controls frame to specify how the Spacing and the Blending of interior grid points should be computed.

You can choose from four methods for computing the spacing constraint:

  • Interpolate: The spacing control is computed by interpolating linearly from the perimeter of the boundary. This gives a smooth variation of spacing that matches the spacing at the perimeter of the boundary. The boundary's arc length is used as the basis for the interpolation. This is the default method.
  • Current Grid: This control maintains the spacing currently in place in the grid.
  • Adjacent Grid: The spacing value is copied from another grid which is selected for the elliptic solver with the current grid and shares the selected boundary. If desired, changes in the adjacent grid can be prevented by setting a relaxation factor of 0.0 on the Attributes tab. If the adjacent grid cannot be determined (either if none exists or if more than one exists), the control is changed to Current Grid. This control provides spacing continuity across grid boundaries.
  • User Specified: Sets the spacing control equal to the value entered in the Value: type in field.

Blending refers to the way in which the boundary control function merges with the interior control functions. The choices are:

  • Linear: The spacing control is blended linearly from the boundary into the interior.
  • Default Exponential: An exponential function is used to rapidly decay the spacing constraint into the grid's interior. This is the default blending function type.
  • Custom Exponential: This allows you to specify a Decay Factor, which is the number of grid points away from the boundary at which the spacing control portion of the boundary control function will be equal to 10% of its boundary value. The default value is 6. Smaller values are more stable, but may dissipate the spacing constraint too quickly. Negative decay values are not allowed.

Demonstration