Use readGrid to prepare the grid file

About the readGrid tool

COREFL needs to read the computational mesh in a fixed format, and readGrid supplies such function. By reading a mesh given in Plot3D format, it generates the files for the simulation.

The readGrid tool will read the “gridFile.dat” and “gridFile.inp”, where “gridFile” is the filename, and output two folders grid and boundary_condition, which should be moved to the input folder and read by COREFL.

The advantage of using such a file is that the corresponding processes need only read their own blocks instead of waiting for asigning. But this may be improved or integrated in COREFL in the future.

The tool is in the folder readGrid. The compilation is straightforward and is omitted here. This code can be compiled on Windows systems. A pre-compiled executable is also given in the folder if anyone uses this tool on Windows before uploading the grid to linux clusters (which is what we do).

Use readGrid

The grid for COREFL is structured grid in Plot3D format. The Plot3D files including name.dat and name.inp contain the grid coordinates and boundary condition information, respectively.

You can generate the grid with a commercial software supporting Plot3D or by writing codes. For example, Pointwise and Gridgen both support this file format. In Pointwise, you choose the solver “Gridgen Generic”, and by exporting CAE, you get those two files.

Note that, we do not have automatic blocking in COREFL. You need to partition the blocks manually when generating grid in softwares if a parallel computation is needed.

The tool gets the information from a file named input.txt, where we need to put the following info into it:

// Gridgen(0) or Pointwise(1)
int GridgenOrPointwise = 1

// Dimension
int dimension = 3
// grid file name
string gridFile = combustor.dat
// boundary file name
string boundaryFile = combustor.inp
// number of processors to use
int n_proc = 2
// if the grid is in ASCII(0) or in binary(1) form
bool isBinary = 1
// if we write the grid in ASCII(0) or in binary(1) form
int writeBinary = 1

// If 2D, set all Z values to the given value
bool setZ = 0
real zValue = 0.0

With the two files, the tool readGrid would generate two folders called grid and boundary_condition, these should be put into the input folder in the work directory.