[几何] Size

SIZE

Use a Size node ([几何] Size插图) to specify the size of mesh elements. It is possible to add Size nodes both as global nodes and as local nodes. If there are several Size nodes in the sequence with a nonempty selection intersection, the mesher uses properties corresponding to the last Size node in the sequence.

Size A meshing sequence corresponding to a nonempty geometry contains a Size node at the first position in the sequence. This Size node, referred to as the default Size node, is defined for the entire geometry and cannot be removed. To override the mesh size settings defined by this Size node, add another Size node to the sequence.

To add this node as a global node, right-click a Mesh node and select Size. To add this as a subnode, right-click a Mesh Operations node and select Size. Also see Global vs. Local Attribute Nodes.

In this section you define the geometric entities where you want to specify a size. Choose the level of the geometry from the Geometric entity level list:

  • Choose Entire geometry to specify the size for the entire geometry.
  • Choose Domain to specify the domains for the size specification. Choose Manual from the Selection list to select the domains in the Graphics window or choose All domains to select all domains.
  • Choose Boundary to specify the boundaries for the size specification. Choose Manual from the Selection list to select the boundaries in the Graphics window or choose All boundaries to select all boundaries.
  • Choose Edge (3D only) to specify the edges for the size specification. Choose Manual from the Selection list to select the edges in the Graphics window or choose All edges to select all edges. This option is only available in 3D.
  • Choose Point to specify the points for the size specification. Choose Manual from the Selection list to select the points in the Graphics window or choose All points to select all points. This option is only available in 2D and 3D.

ELEMENT SIZE

In the Calibrate for list, select the physics node for which the element size is calibrated. The options available in some cases require module-dependent physics interfaces as indicated. In all cases, the default values for the Element Size Parameters are adjusted for the type of problem being solved.

  • For any module, General physics and Fluid dynamics are options.
  • If you have the Plasma Module and are using one of its plasma interfaces, choose Plasma from the Calibrate for list.
  • If you have the Semiconductor Module and are using the Semiconductor interface, choose Semiconductor from the Calibrate for list.

The default element size is Predefined and set as Normal. See Mesh Element Quality and Size and Predefined Mesh Element Sizes for details about the options. This automatically determines the parameters that you can otherwise customize under Element Size Parameters.

Select Custom if you want to change the value for any parameters in the Element Size Parameters section.

Element Size Parameters

This section is available when Custom is selected as the Element Size. Specify all element size parameters using numerical values or user-defined parameters.

The following parameters control the mesh element size (the parameters where you define a size use the geometry’s length unit). Defaults vary based on whether it is a default node or not. Edit the default values as required for the following fields:

  • Maximum element size: Use this parameter to limit the allowed element size, for example, if you want to limit the maximum element size to a fraction of the wavelength to make sure that the wave propagation is fully resolved. By using a parametric sweep to vary the maximum element size, you can solve the model using meshes with different mesh density to study how it affects the solution.
  • Minimum element size: Use this parameter to specify the minimum allowed element size. You can use this value to, for example, prevent the generation of many elements around small curved parts of the geometry. If some details of the geometry are smaller than the minimum element size, the mesh will contain elements of a smaller size in order to resolve the geometry. This parameter is not available in 1D.
  • Maximum element growth rate: Use this parameter to determine the maximum rate at which the element size can grow from a region with small elements to a region with larger elements. The value must be greater or equal to one. For example, with a maximum element growth rate of 1.5, the element size can grow by at most 50% (approximately) from one element to another.
  • Curvature factor: Use this parameter to determine the size of boundary elements compared to the curvature of the geometric boundary (that is, the ratio between the boundary element size and the curvature radius). The curvature radius multiplied by the curvature factor, which must be a positive scalar, gives the maximum allowed element size along the boundary. A smaller curvature factor gives a finer mesh along curved boundaries. This parameter is not available in 1D.

Resolution of narrow regions: Use this parameter to control the number of layers of elements that are created in narrow regions (approximately). The value must be a nonnegative scalar. A higher value gives a finer mesh in narrow regions. If the value of this parameter is less than one, the mesh generator might create elements that are anisotropic in size in narrow regions.

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