Turbulent Flow in a Micro-channel

Turbulent flow of water in a narrow gap of an emulsifier is investigated experimentally using micro-PIV (micro Particle Image Velocimetry) technique and compared with numerical predictions performed using the commercial code Fluent. The purpose of the investigations is to develop a procedure for wellcontrolled generation of mono-disperse suspension of micro droplets. These droplets will form a matrix for collection of nano-particles into well-structured configuration [1]. The micro-flow measurements are based on epi-fluorescence illumination and high-speed imaging. The experimental data are compared with the numerical results obtained using both turbulent and laminar flow models. It was found that, due to small channel dimensions and very small flow development length, the turbulent energy dissipation takes place mainly in the gap and shortly behind it. Very low amount of oil-phase fraction in investigated emulsions justifies us to use mean energy dissipation estimated for pure water to predict mean diameter of oil droplets. These predictions are validated using experimental data for the emulsion. NOMENCLATURE Symbol Description Unit QV Volumetric flow rate m /s QM Mass flow rate kg/m 3 V Velocity m/s V Mean value of velocity m/s V ′ Fluctuation of velocity m/s Re Reynolds number dimensionless d Diameter m ρ Density kg/m σ Interfacial tension N/m