Modified model of bubble formation in non-Newtonian fluids

Based on the comprehensive forces balance model,a modified model of the formation of a single bubble in non-Newtonian fluid under constant flowrate was developed by taking account of the effect of the ingoing gas through orifice as well as its variation OH the radial expansion of bubble.The modified model involves the radial expansion equation of bubble surface and the forces balance equation in vertical direction of the bubble respectively.The shape variation of bubbles formed in polyacrylamide(PAM)aqueous solutions under various conditions was predicted numerically.The practical formation of bubbles was real-time visualized and recorded by a CCD camera and a computer by means of a special laser image measurement system.Results show that the predicted shapes of the bubbles by the present model agree well with experimental observation.