A boundary layer atmospheric model is built with the help of the method of closing the system of the turbulent energy equation and turbulent dissipation rate equation. The conventional meteorological observation data at single station are used to calculate the characteristic parameters inside and outside the atmospheric boundary layer and to calculate the vertical profile of meteorological elements. The computational result reproduces the structural feature of boundry layer.

A k ε model based on the renormalization group theory(RNG k ε model) has the same form as the standard k ε model, but it includes an extra term in the dissipation rate equation through C * 1 that describes the effect of large distortion and incorporates some anisotropic effects.

Let therelax factors of the momentum equations are equal to 0.5, the relax factors of the turbulent kinetic energy equation and the turbulent dissipation equation are equal to 0.4. the method of pressure adjust (Method of Primitive Variables) is applied to calculate the pressure.

According to effects of destabilization and stabilization of rotating system, two modifications are proposed to correct ε equation of standard k ε model.

The mathematical model, describing the flow phenomena in the tundish, was established according as the continuity equation, N-S equation, K equation, s equation and energy equation, meanwhile the FLUENT commercial software was used to calculate.

There were similarity solutions in the uniform environment for the system of equations including the equation of continuity,the equation of momentum along the flow direction and concentration,and equations of k,epsilon.

In this thesis,based on dimensional analysis, we use mass-weighed averaged unified second-order moment (MUSM) method and probability density distribution function (PDF) method separately, to construct the explicit algebraic expressions of fluid-particle correlated dissipation rate and fluid-particle correlated turbulence kinetic energy.

A Dissipation Rate Equation for Low-Reynolds-Number and Near-Wall Turbulence

These problems could be traced to the modeling of the dissipation rate equation.

In this paper an attempt is made to improve the modeling of the dissipation rate equation so that it could successfully predict both free and wall-bounded shear flows including plane wall jets and backstep flows.

The particle kinetic energy equation for two-scale fluctuation, particle energy transfer rate equation for large-scale fluctuation, and particle turbulent kinetic energy dissipation rate equation for small-scale fluctuation are derived and closed.

The isotropic approach is based on Kolmogorov's hypothesis and a dissipation rate equation modified to account for vortex stretching.

This paper presents a numerical technique for calculating the steady turbulent flow of a incompressible fluid around the stern of body of revolution and its wake by using a streamline iteration method. The turbulence model used is a two-equation (K-ε) model devoloped by Harlow and Nakayama. In this numerical calculation, however, there are some features:1) The convection terms of governing equations for total pressure, turbulent kinetic energy and its dissipation rate in turbulent flow are written in the form...

This paper presents a numerical technique for calculating the steady turbulent flow of a incompressible fluid around the stern of body of revolution and its wake by using a streamline iteration method. The turbulence model used is a two-equation (K-ε) model devoloped by Harlow and Nakayama. In this numerical calculation, however, there are some features:1) The convection terms of governing equations for total pressure, turbulent kinetic energy and its dissipation rate in turbulent flow are written in the form of the variations of tlvese variables along streamlines, and for static pressure the radial pressure gradient equation is used. In this form, these equations can be more eonvienicntly be dealt with in numerical calculation. 2) By means of a system of coordinate transformations, the external flow field extending to infinity in both radial and axial directions is transformed into an internal flow field within a finite region. Therefore, free-stream condition and parabolic flow condition may be used on the outer boundary and downstream boundary repectively. The boundary layer flow and potential flow outside can be resolved by an uniform system. 3) Assumptions for a thin boundary layer and partially parabolic flow, etc. are not needed.A numerical example is gaven to show the fair agreement between the theoretical predition by the present method and experimental results.

Starting from the fundamental equations for viscous flow, and using gene-ralized tensor form, this paper strictly derives the exact transport eqtations ofthe Reynolds stress, and of the turbulent kinetic energy as well as of the rateof turbulent kinetic energy dissipation for three-dimensional incompressible steadyflows in general rotating and non-orthogonal curvilinear coordinate systems.Acocrding to conventional simpifying assumption, based on the exact transportequations mentioned above, the correct tensor...

Starting from the fundamental equations for viscous flow, and using gene-ralized tensor form, this paper strictly derives the exact transport eqtations ofthe Reynolds stress, and of the turbulent kinetic energy as well as of the rateof turbulent kinetic energy dissipation for three-dimensional incompressible steadyflows in general rotating and non-orthogonal curvilinear coordinate systems.Acocrding to conventional simpifying assumption, based on the exact transportequations mentioned above, the correct tensor expression of k-ε two-equationturbulence model in general curvilinear coordinate systems is derived, and thenthe arguments for the corresponding equations as advanced in [1], [2] and [10]are questioned.

Based on experimental results, a three-dimension two-phase flow physical model of the mixing chamber in Y-jet is set up. A mathematical model related to the physical model is also established. The numerical computation method is used to investigate and predict the flow fields. In order to consider the effecf of the interface wave between gas and liquid phase, an "Interface function" is proposed, the effect on effective viscosity caused by the existing liquid droplets in the gas phase is also considered in the...

Based on experimental results, a three-dimension two-phase flow physical model of the mixing chamber in Y-jet is set up. A mathematical model related to the physical model is also established. The numerical computation method is used to investigate and predict the flow fields. In order to consider the effecf of the interface wave between gas and liquid phase, an "Interface function" is proposed, the effect on effective viscosity caused by the existing liquid droplets in the gas phase is also considered in the numerical computation. A k-ε turbulcnt model is used in the computation of the gas phase. The numerical computation method is also employed to solve the equations of three-dimensional continuity, momentum, tubulent energy and dissipation. It is show that the computational program can be used to handle the problems of pressure, velocity, turbulent fields and liquid film thinckness of the mixing chamber in Y-jet. A comparison is made between the prediction of the pressure fields and the experimental data. Finally, some thoughts are proposed to improve the mathematical model.