[adam14qin]

I have inlets that are coaxial nozzles. The inlet fluid entering the simulation domain from the coaxial nozzles.

Initially, I use two phase flow in VOF. Both the inner nozzle and outer nozzle have the same fluid (Dichloromethane) whereas the primary phase is air and the secondary phase is DCM. The two flows from coaxial nozzles merge into one jet. The spraying process is very stable.

Later I want to monitor the individual flow of each nozzle. Hence I set the inner nozzle fluid as the phase 2 and the outer nozzle fluid as phase 3. Both the phases are the same fluid DCM. During simulation I found the phase contour displays abnormal that the inner flow phase contains outer flow phase, which is not possible. Moreover, I found the fluid flow surface becomes not so smooth as two phase flow, singularities are spotted on the air-liquid interface.

Can someone kindly offer me suggestions to improve my method?