# Adjustment: meshing by deviation (on the lines/ non flat faces)

## Introduction

Adjustment of the deviation permits cutting the meshing elements of the curved objects in a project :

- cones, cylinders, distorted faces … (for the faces in 3D)
- arcs of circle, left lines (for the lines)

## Principle

The division is illustrated in the figure below. The arc of circle is cut up to a certain limit set by the user.

## Definition

For a line element, the criterion of deviation corresponds to the distance d measured between the centre of the line element and its projection on to the curved line.

## Cutting by deviation

Schematically, on a curve line, for each linear element it should be checked that the deviation should be inferior to the maximal value of deviation defined during the adjustment by the user. If this condition is not checked, our arc is cut into two and so on, up to the attainment of the maximal deviation distance.

## Types of deviation

The meshing by deflection can be applied to lines and to faces. The value of the deviation can be relative or absolute. The different types of deviation in function of their assignment are presented in the following table:

Element | Type | Value |
---|---|---|

Deviation on the faces (including or not the infinite box) | relative | 0 < d < 1 |

absolute | Absolute dimension in meter | |

absolute | Value defined by a relationship between the max. dimension of the project and the max. dimension of the deviation | |

Linear discretization of the deviation type | relative | 0 < d < 1 |

absolute | Absolute dimension in meter |

## Aided mesh

For each project, the software creates an aided_meshline instance (for the deviation on non flat lines) and an aided meshgenerator (for the deviation on non flat faces in 3D) dedicated to the Aided mesh.