# AnnularMeshGenerator

## Overview

This MeshGenerator object creates a mesh with an annular shape, and Quad4 elements distributed on several rings. The user can choose the inner and outer radii, as well as the number of elements in the radial and angular directions.

It is also possible to create a disc-shaped mesh with this class. To do so, the user has to choose 0 for the value of the inner radius. This will create a mesh composed of Tri3 elements at the center of the disc, and Quad4 everywhere else.

If and , this will create a fraction of an annulus or disc.

## Description

The AnnularMesh mesh generator builds simple 2D annular and disc meshes. They are created by drawing radial lines and concentric circles, and the mesh consists of the quadrilaterals thus formed. Therefore, no sophisticated paving is used to construct the mesh.

The inner radius and the outer radius must be specified. If the inner radius is zero a disc mesh is created, while if it is positive an annulus is created. The annulus has just one subdomain (block number = 0), whereas the disc has two subdomains: subdomain zero consists of the outer quadrilaterals, while the other (block number = 1) consists of the triangular elements that eminate from the origin.

The minimum and maximum angle may also be specified. These default to zero and , respectively. If other values are chosen, a sector of an annulus, or a sector of a disc will be created. Both angles are measured anticlockwise from the xx axis.

The number of elements in the radial direction and the angular direction may be specified. In addition, a growth factor on the element size in the radial direction may be chosen. The element-size (in the radial direction) is multiplied by this factor for each concentric ring of elements, moving from the inner to the outer radius.

Sidesets are also created:

• Sideset 0 is called "rmin" and is the set of sides at the minimum radius (which is zero for the disc).

• Sideset 1 is called "rmax" and is the set of sides at the maximum radius.

• Sideset 2 is called "tmin" and is the set of sides at the minimum angle, which is created only in the case of a sector of an annulus (or disc)

• Sideset 3 is called "tmax" and is the set of sides at the maximum angle, which is created only in the case of a sector of an annulus (or disc)

## Input Parameters

C++ Type:double

Options:

• rminInner radius. If rmin=0 then a disc mesh (with no central hole) will be created.

C++ Type:double

Options:

Description:Inner radius. If rmin=0 then a disc mesh (with no central hole) will be created.

• ntNumber of elements in the angular direction

C++ Type:unsigned int

Options:

Description:Number of elements in the angular direction

### Required Parameters

• tmin0Minimum angle, measured anticlockwise from x axis

Default:0

C++ Type:double

Options:

Description:Minimum angle, measured anticlockwise from x axis

• tmax6.28319Maximum angle, measured anticlockwise from x axis. If tmin=0 and tmax=2Pi an annular mesh is created. Otherwise, only a sector of an annulus is created

Default:6.28319

C++ Type:double

Options:

Description:Maximum angle, measured anticlockwise from x axis. If tmin=0 and tmax=2Pi an annular mesh is created. Otherwise, only a sector of an annulus is created

Default:0

C++ Type:unsigned short

Options:

Description:The subdomain ID given to the QUAD4 elements

• tri_subdomain_id1The subdomain ID given to the TRI3 elements (these exist only if rmin=0, and they exist at the center of the disc

Default:1

C++ Type:unsigned short

Options:

Description:The subdomain ID given to the TRI3 elements (these exist only if rmin=0, and they exist at the center of the disc

• growth_r1The ratio of radial sizes of successive rings of elements

Default:1

C++ Type:double

Options:

Description:The ratio of radial sizes of successive rings of elements

• nr1Number of elements in the radial direction

Default:1

C++ Type:unsigned int

Options:

Description:Number of elements in the radial direction

### Optional Parameters

• control_tagsAdds user-defined labels for accessing object parameters via control logic.

C++ Type:std::vector

Options:

Description:Adds user-defined labels for accessing object parameters via control logic.

• enableTrueSet the enabled status of the MooseObject.

Default:True

C++ Type:bool

Options:

Description:Set the enabled status of the MooseObject.