# Extrusive mesh generator

## Definition

An extrusive mesh generator generates a face or volume mesh in layers on domains obtained by extrusion.

Mesh elements obtained are as follows:

face elements (extrusion of a line)

Rectangle, Quadrangle

volume elements (extrusion of a face)
Prism, Pentahedron Parallelepiped, Hexahedron

## Limitation of use

The use of the extrusive mesh generator is limited to faces / volumes obtained by extrusion using a transformation of the following type:

• translation
• rotation
• affinity with a positive ratio

## Principle

Let's consider two faces, one of them (the image face) is obtained by extrusion from another (the source face) using a transformation.

The extrusive mesh generator, defined by this transformation, produces a layered mesh of a volume.

The mesh of the volume is defined by:

• the mesh on the source face is either automatic mesh (triangles) or mapped mesh (rectangles);

extruded faces (image faces) have the same mesh as their source faces

• the number of elements in the direction of extrusion is set by one of the lateral lines, the reference line

## Connection with geometry

If in the geometry context a building option… and associated extrusive mesh generatorwas activated during the extrusion phase, then the extrusive mesh generator has already been created and assigned to the corresponding faces / volumes.

## Source entity

If an extrusive mesh generator is used, the following questions may arise:

• How to find the source face (or reference face)?
• How to find the source line (or reference line)?

By editing an image face it is possible to know its source face:

• from the dialog box, click on Mesh tab, and check the following field: … Face which imposes its mesh to the current face .

By editing an image line, it is possible to know its source line:

• from the dialog box, click on Mesh tab, and check the following field: … Reference line for the mesh of the line .

## Mesh adjustment

The mesh adjustment is carried out:

• on the source face
• on a line in the direction of extrusion

## Reference line

The number of layers in the extrusion direction is imposed by the mesh of one of the lateral lines, the reference line .

This line is chosen by Flux, according to the following rules:

• If there is no line with a mesh line, the line with the smallest index number becomes the reference line.
• The only line with a mesh line becomes the reference line.
• The line with the smallest index number and with an arithmetic mesh line becomes the reference line.
• The line with the smallest index number and with a non-arithmetic mesh line becomes the reference line.