secondary breakup model
 

Hi all,

I am trying to set up a user difined secondary break up model in drobrk.f. But there are still some points unclear:
1.What do XD,YD,ZD stand for. Are they instantaneous position of a certain parcel or are they fixed as the initial position of a certain parcel?
2.What is the relationship between XD,YD, ZD and DRC(IDR, I) listed in drop.inc?
3.What is the relationship between XD,YD,ZD between Xc,Yc,Zc, which are the input of nozzle origins in the GUI? How to pass the GUI input nozzle origins to drobrk.f, since I am try to trigger the secondary breakup for the parcel considered after a certain breakup length.
4.similar to question 1, how about UD,VD, WD and DRV(IDR,I)?

Thanks in advance for your kindly sharing your experiences