W.L. Wei

Large Eddy Simulation of Gas-Liquid Two-Phase Flow for a Nested Type Fixed-Cone Valve

large eddy simulation cooperated with a physical fractional-step method is applied to simulate steady flow around a nested type fixed-cone valve; and the equations are solved with the finite volume method. The free fluid surface is simulated by the VOF method. The pressure contours and vorticity magnitude are obtained. The modeling results conform to physical law, and show that the large eddy simulation theory has powerful capacity in simulation of microstructures of turbulent flows, and the function of the nested type fixed-cone valve for energy dissipating is good.

Large Eddy Simulation of the Gas–Liquid Flow in a Cylindrical Cross-Sectioned Bubble Column

This paper is concerned with the numerical study of gas–liquid flow in bubble columns by large eddy simulations (LES). The Euler–Euler approach is used to describe the equations of motion of the two-phase flow. The mean velocities and the fluctuating velocities are obtained. It is found that, when the drag, lift and virtual mass forces are used, the computed results in agreement with experimental transient behavior can be captured.

Simulation of of 3D Flood Waves by Gas-Liquid Two-Phase Model

This paper is concerned with a gas-liquid two-phase model combining with the k–ε turbulent model for numerical simulation of 3D flood waves due to complete or partial dam-break. The flow equations are solved with the finite volume method and solved by the pressure-correction algorithm of the SIMPLE-type. The free fluid surface is simulated by the the volume of fluid(VOF) method. The comparisons with other numerical results show that the proposed method is accurate, reliable and effective in simulation of dam-break flood waves.

Investigation of Effects of Baffle Configuration on the Performance of a Fixed-Cone Valve by Gas-Liquid Two-Phase Model

Nested type Fixed-Cone Valve, numerical simulation, energy dissipating, turbulent flow Abstract: In this paper, In this paper, a new type of Fixed-Cone Valve was proposed by improving the conventional type Fixed-Cone Valve .The flow fields of the two kinds of Fixed-Cone Valves were studied by using numerical simulation method .The computed pressure fields and the velocity fields were analyzed ,which shows that under the same conditions ,and by using the nested Fixed-Cone valve, the pressure of the upstream pipe and the cone valve and the average velocity along the downstream pipeline are reduced ,but the rate of energy dissipation is increased.

2D Simulation of Flow Field of Horizontal Sedimentation Tank

In this paper, we use 3D time-averaged equations and the 3D k-ε turbulence model to numerically simulate the flow in a horizontal sedimentation tank. The PISO algorithm is used to couple velocity and pressure. The results show that the model can provide a reference in designing sedimentation tanks.

Investigation of the Submerged Depth of Aeration Impellers in an Oxidation Ditch by Numerical Simulation

In this paper, the flow structure of the oxidation ditch was studied using numerical simulation method and different submerged depth of aeration impellers. The computed velocity fields were analyzed, which shows that under the same conditions, and by using the optimal submerged depth the average velocity of the flow in oxidation ditch is increased and the velocity near-bottom has increased significantly. The results of comparisons show that the velocity distribution is more uniform along the depth direction, and that the flow velocity distribution structure can prevent sludge from settling in the oxidation ditch processing system at the submergence ratio called the optimal submergence ratio, which helps to improve the efficiency of oxidation ditch sewage treatment system.

A CFD Methodology for Solid and Liquid Flow Fields of Sedimentation Tanks

In this paper, the CFD approach is used to study the solid–liquid two-phase turbulent flow and sludge concentration distribution in a secondary sedimentation tank. By the simulation, the velocity and the turbulent kinetic energy and turbulent kinetic energy dissipation rate and solid distribution in a secondary sedimentation tank are obtained, which shows the simulation model is an effective method to investigate the flow patterns and their influence on the process inside the sedimentation vessel.

Numerical Simulation of Flow on Stepped Spillway Combined with Wide Tailing Piers and Stilling Basin

In this paper, a two-phase flow model combined with the Realizable k–ε turbulence model was used to simulate hydraulic characteristics of two-type dissipaters: the stepped spillway combined with stilling pool and the stepped spillway combined with wide tailing pier and stilling pool. The distributions of physical parameters, such as velocity field, pressure field, turbulence kinetic energy and turbulence dissipation rate were obtained. The grid was generated by using the regional division method, the unstructured grids used for the irregular and complex parts and the structured grids for the regular and simple parts, and the grid density is arranged according to the flow gradient size. The finite volume method was adopted to discretized the control equations; and the VOF method was adopted to deal with the free water surface; and the PISO algorithm was used to solve the velocity and pressure coupling equations. A comparative analysis of the two energy-dissipators in the velocity field, pressure field, turbulence kinetic energy and turbulence kinetic energy dissipation rate shows that the dissipation of overflow for a stepped spillway together with wide tailing piers and a stilling pool jointing energy dissipator is better than that with pier situation.

A Two-Fluid Model for Water Drop Falling

In this paper, a numerical two-phase flow model combining with the Realizable k–ε turbulent model for compressible viscous fluid is presented for the computation of water drop falling characteristics; and the equations are solved with the finite volume method. The free fluid surface is simulated by the VOF method. A multigrid technique based on the full approximation storage (FAS) scheme is employed to accelerate the numerical convergence. The numerical results for water drop suggest that this basic model can be used to study violent aerated flows, especially by providing fast qualitative estimates.

Research on the Shape of Oxidation Ditch Diversion Wall

Diversion wall can improve bend flow patterns in an oxidation ditch. In this paper, a non-equal thickness diversion wall was proposed, and studied by numerical simulation method. The simulated velocity field of the new shape of oxidation ditch diversion wall was compared with that of the common shape diversion wall under the same boundary conditions, which shows that the new shape can better improve the bend flow patterns in an oxidation ditch, and reduce the size of the backflow area and increase the high-velocity region in the channel.