Pressure Difference for Moving Nitrogen Bubbles in a Waving Duct

A duct with varying cross-sections can show some essential features of the motion of foam in porous media. In this paper, the effective viscosity of the bubbles train moving through cylindrical ducts with sinusoidal cross-section was experimentally measured. The test tube has total length of 1.14 m and has constrictions at interval of 0.0095 m. It is found that the foam effective viscosity is much higher than water viscosity and it is possible to extend the foam rheology correlations in constant cross section ducts to predict the flow differences in waving ducts.