[waveandwind]

Hi everyone. I have a problem in the udf (FLUENT) and dont know how to start it.
I want to find a particular group of cells, i.e. located by coordinates in a cylinder region, and save these cells' index (or threads?) for further uses.
Now I think I am surposed to use:




begin_c_loop_int(cc,tc)
C_CENTROID(xrc,cc,tc);
if xrc<=...
{
Record cc. How to record all the cells in a variable？

}
end_c_loop_int(cc,tc)


Moreover, if I have the cell group cc, how can I get the thread of these recorded cells?

So I can allocate memory and define sources to these cells...


Thank you in advance!

[gearboy]

Originally Posted by waveandwind

Hi everyone. I have a problem in the udf (FLUENT) and dont know how to start it.
I want to find a particular group of cells, i.e. located by coordinates in a cylinder region, and save these cells' index (or threads?) for further uses.
Now I think I am surposed to use:




begin_c_loop_int(cc,tc)
C_CENTROID(xrc,cc,tc);
if xrc<=...
{
Record cc. How to record all the cells in a variable？

}
end_c_loop_int(cc,tc)


Moreover, if I have the cell group cc, how can I get the thread of these recorded cells?

So I can allocate memory and define sources to these cells...


Thank you in advance!

You can allocate a dynamic dimension to store these cell number.

cell_t *DimensionToStore=NULL;
int total_cells=0, cell_index;
begin_c_loop_int(cc,tc)
C_CENTROID(xrc,cc,tc);
if xrc<=...
{
total_cells++;
}
end_c_loop_int(cc,tc)

DimensionToStore=(cell_t*)malloc(total_cells*sizeo f(cell_t));

cell_index=0;
begin_c_loop_int(cc,tc)
C_CENTROID(xrc,cc,tc);
if xrc<=...
{
DimensionToStore[cell_index]=cc;
cell_index++;
}
end_c_loop_int(cc,tc)

Now DimensionToStore is ready for use. Do not forget to free it since it is a dynamic dimension, otherwise memory leakage will occur.

[gearboy]

Originally Posted by gearboy

You can allocate a dynamic dimension to store these cell number.

cell_t *DimensionToStore=NULL;
int total_cells=0, cell_index;
begin_c_loop_int(cc,tc)
C_CENTROID(xrc,cc,tc);
if xrc<=...
{
total_cells++;
}
end_c_loop_int(cc,tc)

DimensionToStore=(cell_t*)malloc(total_cells*sizeo f(cell_t));

cell_index=0;
begin_c_loop_int(cc,tc)
C_CENTROID(xrc,cc,tc);
if xrc<=...
{
DimensionToStore[cell_index]=cc;
cell_index++;
}
end_c_loop_int(cc,tc)

Now DimensionToStore is ready for use. Do not forget to free it since it is a dynamic dimension, otherwise memory leakage will occur.

If you use UDF compling/debugging tool VcUdfStudio (https://vcudfstudio.bitbucket.io/), you also can use C++ "new"/"delete" operator to allocate dynamic dimensions.

DimensionToStore=new cell_t[total_cells];

...
delete[] imensionToStore;

[waveandwind]

Originally Posted by gearboy

You can allocate a dynamic dimension to store these cell number.

cell_t *DimensionToStore=NULL;
int total_cells=0, cell_index;
begin_c_loop_int(cc,tc)
C_CENTROID(xrc,cc,tc);
if xrc<=...
{
total_cells++;
}
end_c_loop_int(cc,tc)

DimensionToStore=(cell_t*)malloc(total_cells*sizeo f(cell_t));

cell_index=0;
begin_c_loop_int(cc,tc)
C_CENTROID(xrc,cc,tc);
if xrc<=...
{
DimensionToStore[cell_index]=cc;
cell_index++;
}
end_c_loop_int(cc,tc)

Now DimensionToStore is ready for use. Do not forget to free it since it is a dynamic dimension, otherwise memory leakage will occur.

Thank you Gearboy! Thats really helpful.
Now given the DimensionToStore which stores the cell index, can I use any loop macro to loop on all these cells?

Something like:
begin_c_loop_int(DimensionToStore)
...

end_c_loop_int(DimensionToStore)