# Ansys Meshing / Use Advanced size functions

‘**Use Advanced Size Function**‘ option gives easy control over sizing functions.

**‘Use Advanced size functions’ control the following properties:**

• Angles between normal for adjacent mesh elements (curvature)

• Number of mesh elements employed in the gaps between two geometric entities (proximity)

• Gradation between the minimum and maximum sizes based on a specified growth rate (all size functions)

Another option of sizing group are explained in this **blog**

**Advanced Size Function options are applicable to the following mesh methods:**

**Volume Meshing:**

• General Sweep (Surface mesh only)

• Thin Sweep (Surface mesh only)

• Hex Dominant (Surface mesh only)

• Patch Conforming Tetrahedron

• Patch Independent Tetrahedron

• CutCell

**Surface Meshing:**

• Quad Dominant

• All Triangles

## Specifying Size Function Options :

The value of the **Use Advanced Size Function **control (**Off**, **On: Proximity and Curvature, On: Proximity,On: Curvature, or On: Fixed**) determines which size function options are available in the Details View. The default is **Off**, unless Physics Preference is set to **CFD**, in which case the default is **On: Curvature**.

**The following options are available in Ansys meshing:**

- Curvature Normal Angle
- Proximity Accuracy
- Num Cells Across Gap
- Proximity Size Function Sources
- Min Size
- Max Face Size
- Max Size
- Growth Rate

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### Curvature Normal Angle

**Curvature Normal Angle**is the maximum allowable angle that one element edge is allowed to span another element edge. It is active only when**Use Advanced Size Function**is set to either**On: Proximity and Curvature**or**On: Curvature**.- You can specify a value from 0 to 180 degrees or accept the default. The default is calculated based on the values of the Relevance and Span Angle Center options.

- Generally for Coarse: 91 to 60 degrees, for Medium: 75 to 24 degrees, & for Fine: 36 to 12 degrees are recommended.
**When Capture Curvature is set to ‘yes, and angle is smaller than setting up angle then it is automatically generating more fine elements in the curved area. fig shows that.**

### Proximity Accuracy

- The proximity size function allows you to specify the minimum number of element layers created in regions that produce “gaps”

in the model. - Proximity Accuracy allows you to control the accuracy level of proximity size function calculations that are performed

between pairs of entities. - The
**Proximity Accuracy**control is available only when**Use Advanced Size Function**is set to either**On: Proximity and Curvature**or**On: Proximity**. You can specify a value from 0 (faster due to calculation but less accurate) to 1 (slower due to calculation but more accurate). The default is 0.5.

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### Num Cells Across Gap

**Num Cells Across Gap**is the minimum number of layers of elements to be generated in the gaps. Available only when**Use Advanced Size Function**is set to either**On: Proximity and Curvature**or**On: Proximity**.- You can specify a value from 1 to 100 or accept the default. The default is calculated based on the value of the Relevance option. If
**Relevance**is 0, the default of**Num Cells Across Gap**is 3. - The value of
**Num Cells Across Gap**is an estimate; it may not be exactly satisfied in every gap.**CutCell**The value of**Num Cells Across Gap**is approximate for meshing. For example, if you specify 3 cells per gap on a narrow face, the final mesh may contain anything between 2-4 cells across the gap.

### Min Size

- Min size is a global minimum allowable element size. It is active when
**Use Advanced****Size Function**is on. - For Min size Specify a value greater than 0 or accept the default.

### Max Face Size

- The Max Face Size specification represents the global maximum allowable size of the elements created by the free surface meshes of the

supported methods.

### Max Size

- Max size is the global maximum allowable element size. It is active only when
**Use Advanced****Size Function**is on. - For Max size, Specify a value greater than 0 or accept the default.

### Growth Rate

- Growth Rate represents the increase in element edge length with each next layer of elements.
- For example, a growth rate of 1.2 results in a 20% increase in element edge length with each next layer of elements.
- It is available when
**Use Advanced Size Function**is on. For Growth rate, Specify a value from 1 to 5 or accept the default. The default is calculated based on the values of the Relevance options.

Another option of sizing group are explained is this **blog**