Water Nozzle and Diffuser

[Nickul]

I want to nozzle a water flow and then diffuse it to slow the jet down. I.e. I need to maintain a pressure up to point and then diffuse it.

If my diffuser is below the 7 deg included angle. Can anybody point me to some design guidelines for the diffuser. I.e. presumably I get to a point where the water , upon opening out, and slowing down, gravity then takes over and it seperates from the diffuser walls.

(I.e. if you imagine this is a vertical arrangement the diffuser could be so large that the water velocity was very low and essentially hanging 'in mid air' in the diffuser, if it did not seperate.)

thanks