Thank you very much Cedric. The project is for a client, so i will use example riv_art to explain my followup problems. I cleared my original problem by using the steering file from example with some tweak. But if I try to open the example in FUDDA, i will get error messages (it should be very easy to replicate this problem in Windows OS). Any idea on why does it happen?
In addition, i am modelling a release duration (e.g. from LT=50 to LT=100) not just a single time stamp. I updated the .f file as attached. But the oil_displacement only includes results for 1156 drogues for each time step, so where are the previous drogues at current time? What i am expecting is 1156 drogues for each LT, and the tracer lasts for the given period.