Hi I want to know about spd files clearly. what kind of data it is. is it just average data of all cells in the geometry at each time step. is there any provision to modify output of spd file so that I can get some other variables as output. please help me. thanks in advance.

Hi
as you said, in the spd file you can find the average data of every quantity of interest, and that data is written at each time step of the computation.
If you use any scalar quantity in your model, then also the mass conc. of that is written at each time step.
I don't know if there's some method to force Star to write a desider quantity...
Hope that help, all the best
Bye! Andrea

thank you Andrea. and I want to calculate concentration of a scalar at a cross section plane. please tell me how can I proceed to do this.

You can try to select every cell on the desired section plane, then you can define a specif cell type for that group of cell and save a *.set file where you store only the new cell set just created. Then you can use the ANALYSIS Control window in the star GUI->Output Controls->Monitoring Engineering Behaviour->Monitoring Cell
Here you can select what scalar to monitor...Star write a file called *.erd where is stored the info that you've selected in the panel of the star GUI.
I've never done something like that on a scalar value, but I use this method for monitoring the momentunm values on an honeycomb...so I think it works also for you!
Bye!