DPM solid cone injection particle tracks not as expected
 

Hi,

I have a solid cone injection of a fluid into an atmospheric domain. The cone injection has a velocity of 17m/s and mass flow of 7e-4kg/s out of a 7.5e-4m diameter hole. The domain is a 36 degree wedge as it is symmetric around the axis. The current spray structure I have is below.

I'm not sure whether the recirculation that appears to be happening is right (I don't think it is) but not sure how to change it. Also, the particles are injected with a rosin rammler distribution and in the early parts of the spray they are correct however in the recirculation zone the droplets appear to be coallescing and the diameter becomes larger than the maximum i have specified.

Domain continuos BC's are pressure outlet at back and top with 0 gauge pressure and no reversed flow. Inlet is velocity of 0.5m/s of air just to help stop velocity vectors getting stuck behind the spray. the domain is large and the image below shows less than one quarter near the injection region.

Does anyone know what could be the issue causing the cone injection to lose its shape as shown?

Thanks