I'm simulating a GDI multihole injector (using STAR 3.26). I'm reproducing a quiescent chamber test. Concerning atomization and secondary breakup, I'm using the built in Star CD model (such as Reitz model). In order to get the correctly penetration and the right diameters of the droplets I'm doing a lot of tuning on the secondary breakup model. Do you think is the correctly way? Could you guve me soma suggetsions?

Use droico ?

I think you need to use droico.f too if you're looking for defining diameters and similar of droplets in your chamber... If you don't want to specify those parameters but you want to obtain it by simulation try also to use Hsiang-Faeth breakup instead of Reitz...I've found some difference in results...

I would like not use a droico subroutine. I think I could use the atomization model (i.e.Reitz) and just tune the secondary breakup model: decresing the WE and TE costant of the model (I mean Reitz-Diwakar one). I would like to find general tuning as for the Diesel spray. Do you have experience about this? Or do you think my considerations are not correct?

If you want to get right diameters of droplets by means of the secondary breakup you can vary We and Te as you said...I think that's a right way to proceed. But you've also said that you're considering a quiet chamber and in the real Diesel engine that's not normal...so proceeding this way you'll get a set of constants for the secondary breakup model that you can only use for simulation in quiet chambers, not in real engine conditions...