Numerical Study On Breakup Of Round Non-Newtonian Liquid Jet With OpenFOAM

Non-Newtonian liquid atomization is an important process in engineering applications such as automotive engines, food processing and chemical industry. However, due to the complexity of non-Newtonian liquid and jet belonging to multiphase flow related to the stability of free surface, solving the problem becomes more difficult. There is no systematic and comprehensive understanding of non-Newtonian liquid atomization. Given the complexity and wide application of Non-Newtonian liquid atomization, the study of this issue becomes a significant research topic that needs be overcome urgently.In this paper, based on the characteristics of power-law type non-Newtonian fluid, combined with the basic fluid mechanics equations, we obtained the constitutive equations and control equations and established a mathematical model and calculation method based on three-dimensional space. In this paper, a numerical study on the dynamic process of non-Newtonian liquid atomization is presented to more fully reveal the mechanism and evolution law of atomization of power-law type non-Newtonian.This work is achieved used the open source CFD code. The dynamic atomization process of non-Newtonian liquid is investigated by the method of numerical simulation. The full transient process of the primary instability, deformation, and fragmentation of interface were simulated by solving the Navier-Stokes equations using an algorithm based on the finite volume method. The liquid-gas interface was tracked using the volume of fluid (VOF) technique and the geometric reconstruction was based on the technique of Piecewise-Linear Interface Construction (PLIC). The LES model is employed to model the turbulence in the jet flow. The continuum surface force (CSF) method is used to describe the surface tension. The physical information of jet flow field was obtained to study the relationship between jet features and parameters. Atomization characteristics of non-Newtonian liquid are analyzed detailedly. The liquid core length and breakup length were redefines in this paper. The distribution of dimensionless liquid core length and dimensionless breakup length were investigated and the results reveal that they have similar characteristics. The relationship between jet parameters (velocity, power-law index, consistency coefficient, ambient pressure, ambient density) and physical information of jet field was discussed, and compared with experimental results. The instantaneous vorticity fields were investigated. Hairpins structures were observed in the outlet region. By comparison with the previous study, we discussed the difference between Newtonian liquid jet and non-Newtonian liquid jet, and got a reasonable physical interpretation. According to the control equations and boundary conditions, the dispersion relation of non-Newtonian liquid jet was derived by using the normal mode method. We analyze the relations between the jet instability and different jet parameters. The results of instability analyzing demonstrated the correctness and reliability of numerical simulations.In present work, through the study and researches on the breaking up of non-Newtonian liquid jet by simulation method, the goal is to improve the understanding of the physical mechanism of non-Newtonian liquid spray and to provide the theoretical basis for practical engineering applications.