Detachment of air bubbles from slit microchannels with shearing flow.

摘要

The flow velocity required to remove an air bubble attached to both surfaces of a slit microchannel was studied. The intent was to quantify the critical flow velocity in terms of bubble contact diameter, Dc, and channel of height, h. First, the critical velocity was determined experimentally. Microchannels ranging from 34--164 microns were constructed for this purpose. Bubbles of various diameters were generated within these channels and a base engine oil was used as the shearing fluid. The critical velocity was found to decrease linearly with both increasing Dc and decreasing h. Second, a model to predict the critical velocity was developed. By equating formulations for the drag force on a bubble to an approximation for the adhesion force, the critical velocity can be calculated. Comparison of model predictions to experimental results show that the model performs well for ratios of D c/h greater than five.