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Hybrid RANS–LES Modeling for Unsteady Cavitating Flow Simulation GUOHUA Gao 1, a, JING Zhao 2,3,b, FEI Ma1,c ,WEIDONG Luo 1,d 1 School of Mechanical Engineering, University of Science & Technology Beijing, Beijing, China 2 School of Mechanism and Vehicle Engineering, Beijing Institute of Technology, Beijing, China 3 School of Astronautics, Harbin Institute of Technology, Harbin,China agaoguohua2011@163.com, bsand810125@163.com, cyeke@ustb.edu.cn, dluowd@ustb.edu.cn Keywords: CFD, Cavitating Flow, RANS-LES Model, Unsteady Abstract.
A typical hybrid RANS-LES approach, DES (Detached Eddy Simulation), was introduced into cavitating flow simulation in this paper.
Menter, are assessed for the simulation of unsteady cavitating flow.
The purpose of this paper is to establish a dependable, robust and accurate computational CFD tool to analyze and minimize the cavitation effects in the design stage of fluid machinery components or systems.
In this paper, the scenario with natural cavitation number 0.6 and Reynolds number 7×105 is used for simulation.

China, email: zys442361@tom.com Keywords: atomization process; Fluent; CFD; numerical simulation; VOF method Abstract.
After applying the VOF method and turbulent model in CFD software Fluent, a numerical simulation was performed to analyze the mechanism of atomization process and some related factors affecting the atomization.
The Analysis of the Numerical Simulation Results A.
The Method of Numerical Simulation.
The Results of Numerical Simulation.

This work has been done a study of the behavior of underground cable based on using a forecasting model that uses the techniques of cfd.
The first phase of the work was making computational model with a cfd software; the second step was the validation of the cfd model by a comparison with the data measured in a experimental model made in laboratory.
The materials considered in the simulations had the following physical properties: Table 1 - Characteristics of the materials used in the simulations.
For brevity we show a small but significant part of the test results comparison which allowed us to validate the CFD model compared to the experimental apparatus.
A mesh geometry was chosen for the simulations which represented an excavation carried out "in a good workmanlike manner."

The Simulation Study of Air Cooler in an Integrated Coal Gasification Combined Cycle System Yan Li1，2，a, Xiumin Jiang2，b, Jiang Wu1，c and Jianxing Ren1，d 1School of Energy and Environmental Engineering, Shanghai University of Electric Power, Shanghai 200090, China 2School of Mechanical Engineering, Institute of Thermal Energy Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China ayli@shiep.edu.cn, bxiuminjiang@sjtu.edu.cn, c wjcfd2002@sina.com, d renjianxing@shiep.edu.cn Keywords: heat transfer; air cooler; CFD; high pressure; IGCC Abstract.
A considerable amount of experimental and simulation works have been done on the prediction of the heat exchanger performance [1–9].
The objective of this work is to investigate the flow field and the heat transfer characteristic of the air cooler in an IGCC by CFD simulation.
The finite volume CFD solver FLUENT6.3 was used to simulate the heat exchanger.
The results of the CFD predictions lead to the temperature distributions, the velocity distribution and the pressure drop distribution.

Ferrari J and Leutwyler used a Plexiglas globe valve to perform experimental testing to observe the formation and location of cavitations, and they performed CFD simulations to better understand and predict its working conditions under different operating conditions [2].
A common method for experimental verification of CFD numerical simulation is to make several special cut-off valves and arrange interfaces in specific areas for data collection [2, 3, 4].
(3) Results of experiments and simulations agree well and the simulation methods are accurate and credible.
Davis, Mike Stewart: Predicting globe control valve performance - Part 1: CFD Modeling.
[7] Srikanth, C., Bhasker, C.: Flow analysis in valve with moving grids through CFD techniques.

Abstract.A computational fluid dynamics(CFD) based numerical model is developed to predict the temperature distribution during Friction Stir Welding(FSW) of dissimilar aluminum alloys.
In this work a Computational Fluid Dynamics(CFD) based model for the heat transfer during dissimilar friction stir welding of AA5083-AA6082 and AA2024-AA7075 is developed using the FLUENT Software.
In the simulation, the temperature along the length at measurement location is divided by the traverse velocity of the work piece to convert the steady state temperature to transient temperature.
Fig. 2 shows the comparison of transient temperature obtained from the present simulation and experimental results of peel et al. [11].
The results of the thermal simulation can be used to predict the viscosity and material flow during the process.

In this paper, an analytical model was developed for a 24-story high-rise public building and CFD was adopted for its numerical analysis.
CFD simulation results for steady condition: model building pressure distribution (z=-5.4m, elevator on the first floor) (a) Exterior window gap flow rate on each floor (b) Elevator landing door gap flow rate on each floor Fig.4.
CFD simulation results for steady condition: gap flow rate.
CFD simulation results for unsteady condition: pressure distribution. t=1.18s, 8.86s, 27.82s, 37.24s were chosen for analysis.
CFD simulation results for unsteady and steady conditions: gap flow rate.

With the rapid evolution of performance of computers and computer application technology, CFD has been extensively used in engineering practice[1].
In order to make up the limited data of automotive wind tunnel, virtual wind tunnel based on CFD is used to describe the inner flow field accurately.
Influence of the regulating seam to open type wind tunnel and the accuracy of simulation need to be discussed more deeply with some simulations [2].
The accuracy of simulation results are better than those of Standard k-ε turbulence model[4].
References [1] Stephane Cyr, Kang-Duck Ih and Sang-Hyun Park.Accurate Reproduction of Wind-Tunnel Results with CFD.

The numerical simulation of cavitating flow in nozzle holes of a vertical multi-hole injector with mixture multi-phase cavitating flow model was carried out.
�ozzle Geometry Based on a four-hole diesel engine injector nozzle, CFD analysis of the cavitating flow in it was carried out.
CFD analysis of the effect of the nozzle geometry on the internal cavitating flow is performed from three aspects.
The mixture multi-phase flow model accompanied with the cavitation model was applied to perform the three-dimension transient numerical simulation for the cavitating flow.
The 3d numerical simulation of the cavitating flow in holes of a vertical multi-hole nozzle using the mixture multiphase cavitating model clearly reveals the 3d nature of the nozzle flow.

The operation simulation of wastewater treatment device based on swirling cavitation degradation has been done by means of CFD software.
Numerical simulation and experimental verification have been done.
Then, use CFD (Computational Fluid Dynamics) software to create its mesh model by finite volume method as shown in Fig. 2.
Simulation result shows that the zone with pressure lower than saturated vapor tension can be formed, and simulation flow rate is 0.671173L/s.
Simulation results of device amplified 10 times is illustrated in Fig. 6.