Flow regimes in a T-mixer operating with a binary mixture

Efficient mixing in small devices is a key target in many processes. Among micro-devices, passive T-shaped micro-mixers are widely used. For this reason T-mixers have been studied in the literature and its working flow regimes have been identified, as well as the instabilities leading to the onset of these flow regimes. However, in most of the available theoretical studies it is assumed that only one working fluid is used, i.e. that the same fluid at the same thermodynamic conditions is entering the two inlet conduits of the mixer. Conversely, the practical use of micro-devices often involves the mixing of two different fluids or of the same fluid at different thermodynamic conditions. In this case the scenario of possible flow regimes can be substantially different from that observed for a single working fluid. To investigate this aspect, the present work aims at identifying the flow regimes in a T-mixers when water at two different temperatures is entering the mixer, the viscosity and density depending on temperature. The effect of the temperature difference on the flow regimes in a 3D T-mixer is investigated by DNS and stability analysis, and the results are compared to the case in which a single working fluid is employed.