Numerical Study On The Interface Tracking Method Of Gas-liquid Two-phase Flow

The gas-liquid two-phase flow is widely existed in life and industry.The moving interface is an important part of the gas-liquid two-phase flow.The movement of the gas-liquid two-phase flow will drive the interface to move continuously,which will lead to complex interface phenomena.The various phenomena of the captured interface not only can get more internal mechanisms of gas-liquid interaction,but also have a huge impact on life and industry.How to deal with two-phase flow,and then get the phase interface,there are two main methods,one is surface method-display tracking method,the other is volume method-implicit tracking method,or Euler method and Lagrange method.The Lagrangian method and the Euler-Lagrangian method in the interface tracking method have low computational efficiency,are not suitable for large deformation,and cannot be applied to the three-dimensional numerical calculation model.Based on the VOF and Level Set method,a kind of research is studied.The Euler motion interface tracking method for calculating the gas-liquid two-phase interface migration characteristics of the three-dimensional model with high efficiency and clear interface.The method uses the Youngs method of the "?" adjacent unit for the motion interface reconstruction,and Youngs-VOF by coupling with the Level Set by geometric methods,the accuracy of the motion interface is improved,and the defects of the VOF and Level Set methods are overcome,and the stability of the high-order derivative itself is avoided to solve the Level Set convection equation and the distance function equation.The "?" shaped adjacent grid Youngs method is used to avoid the situation that the captured interface was blurred due to numerical dissipation and numerical dispersion,as well as nonlinear effects.The Youngs-VOF coupled Level Set method not only ensures the stability of the computing interface,but improves the computational efficiency compared with the Lagrangian method.Firstly,the Youngs-VOF coupled Level Set method is used to numerically calculate the circular motion interface model in the classical rigid body translation and shear flow field.The pressure-velocity coupling algorithm uses the PISO algorithm and the momentum equation uses the second order upwind scheme discretization.The Level Set equation uses the first order upwind scheme discretization,and the shear flow field is encoded using UDF.Compared with the literature VOF method,Youngs-VOF coupled Level Set method can better maintain the shape of the rigid body,and the interface is more clear and sharp.Secondly,the Youngs-VOF coupled Level Set method and the VOF method are used to numerically calculate the rise of a single bubble in water.The pressure-velocity coupling algorithm uses the PISO algorithm,the momentum equation uses the second order upwind scheme discretization,and the Level Set equation uses the first order upwind scheme discretization.Compared with the experimental results,the validity of the Youngs-VOF coupled Level Set method is verified and the interface is clearer and sharper than the VOF method.Finally,the Youngs-VOF coupled Level Set method is used to numerically calculate the dam-free surface flow process.The pressure-velocity coupling algorithm uses the PISO algorithm,the momentum equation uses the second order upwind scheme discretization,and the Level Set equation uses the first order upwind scheme discretization.The stability of the Youngs-VOF coupled Level Set method and its applicability to the three-dimensional numerical model are verified by comparison with experiments.