Geometrical parameters have great influences on the formation of gas bubbles or liquid droplets in the microchannel.The effects of gas inlet angle and cross-section aspect ratio on gas-liquid flow in the microchannel were investigated numerically by employing the volume of fluid (VOF) method.Generally

Taylor flow pattern could be observed in microchannels with various gas inlet angles and cross-section aspect ratios.A uniform distribution of bubble length could also be obtained under most circumstances.It was found that a 60° gas inlet angle helped to generate shortest bubble when cross-section aspect ratio was in the range of 0.5 to 2

while bubble length reached a minimal value when gas inlet angle was 45° and cross-section aspect ratio was 4 or 8.The dimensionless bubble length increased with increasing cross-section aspect ratio

and poor uniformity of bubble length distribution was observed when cross-section aspect ratio became larger.More specifically

a non-uniform bubble length distribution was observed when cross-section aspect ratio reached the value of 8.