Numerical and dimensional analysis for the jet buckling of highly viscous fluid

Abstract

Jet buckling of highly viscous fluid is a common phenomenon both in nature and industry. In order to effectively understand this phenomenon, experiments, numerical simulation and dimensional analysis are employed with the jet buckling of rubber melt and in injection molding. To begin with the construction of two high-resolution discretization schemes for convection terms, a three dimensional algorithm for liquid jet buckling phenomenon is established based on two phase flow model and discretization via finite volume method. The developed algorithm shows its good accuracy and stability for jet buckling simulation. The numerical results are in good agreement with experimental results obtained by camera directly and short shot experiments. It is found shear rate and gravity have an effect on jet buckling. Compared to non-buckling, buckling of liquid occurs at high shear rate. Direction of gravity influences the length of jet and the pattern of buckling. Furthermore, dimensional analysis of buckling is carried out based on experimental and numerical results. Results reveal that the influence of gravity on buckling is greater when gravity is vertical than parallel to velocity. Dimensional analysis illustrates that shear rate has a greater effect on buckling frequency than hydraulic radius of inlet, length of cavity, gravitational force, viscous force and kinematic viscosity. The buckling frequency is approximately proportional to the square of the shear rate.