Computational Fluid Dynamics initiated in structured grid context for smooth and orthogonal structured grid on relatively simple geometries. Today, CFD has evolved encompass multi block and overlapping structured grid techniques for complex geometries, along with other mesh types such as tetrahedrals, polyhedrals, and prisms.

The quality and convergence of the CFD solution is predictably linked to the quality of the mesh used.  Structured meshes are normally accepted as being of higher quality than unstructured meshes, but can be more difficult to generate for complex geometries.  

CFD-GEOM is an ideal meshing tool for generating the multiblock structured grids. It has a rich set of features and options enabling user to create the multiblock structured meshes with ease.  The example shown in Figure 1 is a good example where multiblock structured meshing works very well.

Figure 1.  Eglin Wing/Pylon/Finned store separation

Previous to CFD-GEOM V2008, automatic multiblock creation was not available, meaning each block had to individually be created by selecting a closed set of six faces.  This new tool eliminates the need to create these blocks individually.

The "Create All Blocks" tool can be found on the Mesh tab under the Structured Block creation tools, as shown in Figure 2. 

Figure 2.   Create All Blocks tool in CFD-GEOM

In order to create all structured domains at once to form a multiblock structured grid, select all the faces and hit ‘Apply’ or middle mouse button in the graphics area.  Also, if no faces are selected, CFD-GEOM will create a block using all faces that are currently viewable in the graphics area.  CFD-GEOM will identify all valid combinations, which consist of a closed set of six faces, and create structured domains for you.

Figure 3 shows a set of faces for an Eglin Wing/Pylon/Finned Store configuration.  At this point, all the faces have been created, but no blocks. 

Figure 3.   Faces created for geometry

Figure 4 show cuts through the newly create blocks.

Figure 4.   Blocks created using Create All Blocks tool

The Limitations of ‘Create all Blocks’ Tool are; 

• This tool accepts four-sided faces (only) to create structured domains. So, faces that have degeneracy will be silently ignored.
• This tool creates only six-sided domains with 1 face per side.

Regards,
Shivakumar GT
ESI CFD Support Team