I am simulating fluid flow in pipe geometry which ends to a nozzle through a converging geometry. The fluid is water and the flow is laminar in the pipe section but it becomes turbulent (Re>2500) in the nozzle section. I need an accurate modeling since I want to compare my results to experimental data. Which turbulence model should I use? Does laminar/turbulent modeling work for my case? If so, how does it recognize the turbulence from laminar flow?