Flow Patterns in a Single Micro-Channel

From the visual studies on the flow patterns for circular, trapezoidal and rectangular channels it may be concluded that as the tube diameter decreases, transitions between flow regimes occur at different combinations of superficial gas and liquid velocities. 

Knowledge of dominant two-phase flow patterns in micro-channels is a key factor in developing accurate and physically sound predictive tools for heat sink design. Unfortunately, interfacial interactions between the vapor and liquid phases during flow boiling in a micro-channel are often far too complex to permit accurate measurement or quantitative assessment of flow patterns. 

---