5 ===============================
6 Principle: the method by blocks
7 ===============================
12 The principle of the method by block is to decompose the geometry to
13 be meshed into a set of hexahedra related per face. The initial
14 geometry is divided into a new geometry which has the property to be a
15 set solids. All these solids are hexahedra with shared faces. Once
16 cutting is complete, the mesh is easy to obtain.
18 The method by blocks consists in:
20 - finding a compound of blocks,
21 - this compound of blocks has to be equivalent to the initial geometry to mesh.
24 A block is a volume defined by:
28 - *straight line*, *curve*
29 - 6 quadrangular faces
30 - *planar face*, *3D face*
32 A compound of blocks is a volume that for each face is:
34 - either a free face (in one block)
35 - or a face shared between 2 blocks
40 Create a model of blocks
41 ========================
43 A model of block is a compound of blocks based on a topological
44 definition. The model of blocks construction can be build by using the
45 two following methods:
47 1. Construct and associate blocks (hexahedra)
48 - the main operations for creating blocks are:
49 - Basics: create, remove,transform
50 - construct hexahedra grids: cartesian, cylindrical, spherical
52 - blocks association operations:
53 - merge, cut, disconnect hexahedra
54 - prism, join quadrangles
55 - merge two quadrangles of two blocks
58 - disconnect two vertices
59 - create hexahedra between two existing quadrangles
61 2. Construct hexahedra via predefined models:
64 - two intersected cylinders
65 - two intersected pipes
67 Example of simple model of blocks
68 =================================
70 .. image:: _static/ex1.PNG
74 2 blocks linked by 1 face