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In this paper, CFD (Computational Fluid Dynamics) method was applied for instantaneous LPG release in an open environment in order to analysis the expansion process of two-phase cloud.
The results from simulation are compared with the published experimental data to validate the model.
The prediction of this flammable cloud dispersion is critical, so some simulation and laboratory work about this issue have been done [3, 4].
Fig. 1 Model set-up Fig.2 Comparison of the mean velocity of droplets at 0.22, 0.32 and 0.4 m Commercial available CFD software FLUENT 6.3.26 was used for simulation.
Fig. 7 Entropy change in 1s Fig. 8 Entropy change in first 0.2s Conclusions This paper presents the successful application of a CFD approach to the simulation of the two-phase LPG cloud expansion from a small-scale instantaneous release.

However, the computing resources of most CFD simulations required are very large, especially some complex problems.Reasonable experimental design method can effectively reduce the number of tests [1].Optimization based on approximate model enables shorten the optimization time several orders of magnitude [2].
Attack angle and ground clearance of the airfoil have a decisive impact on the CD and CL[3].In this paper, the optimal results obtained based on the response surface model instead of CFD simulation program.
Sample points of different group Numerical Simulation NACA2412 airfoil was selected.
Model Establishment and Verification By using CFD method, the results of each sample point were placed in table 1.
This method is very when the simulation need huge computing resources and computing time.

Effect of Piston Shape on Scavenging in a Two-Stroke Engine - A CFD Analysis Vivek Agrawal1, a, J.
The CFD solution has been obtained by using commercial CFD code STAR-CD.
First, the CFD results are compared with those of experimental values obtained from particle image velocimetry (PIV).
Free piston two-stroke engine was also optimized for higher scavenging efficiency using CFD [6].
(a) From PIV experiments (b) From CFD simulation Fig.2.

Experiments of 300 mm wafer ashing 300 mm wafer asher, SUPRA-V+ (PSK Inc.) was modeled and calculated to check the validity of the CFD simulation.
From CFD simulation, temperature distribution in the chamber and oxygen radical flux distribution over wafer surface were calculated as shown in Fig. 3 and compared with these measurements.On the wafer surface oxygen radicalsare distributed evenly by diffusion, and higher density was observed in the vent plate and exhaust line.
(Fig.3)Results of CFD simulation;(a) Temperature distribution and(b) Velocity vector pattern.
(Fig.4)CFD simulation result;(a) Temperature and (b) Velocity variationsover 450 mm wafers.
(Fig.5) CFD simulation result;(a) Density and (b) Flux variations over 450 mm wafer.

Fig.1 Imaginary flow pathway of the brake condition In order to explore flow mechanism of tractive and brake process of HTRA, numerical simulation of flow field was studied by Xiang and Li etc [3~4].
So in this paper CFD numerical simulation was implemented to evaluate the relationship between rational speed of pump wheel and brake torque of D490 HTRA by general commercial software CFX.
Brake performance analysis The numerical simulation method based on computational fluid dynamics (CFD) was applied in this paper to calculate this runaway speed.
The contrast curves of CFD calculation results and the test results was shown in Fig.8, wher TPtest and TTtest was separately the test results of the pump and the turbine torque , their difference Ttest was the brake torque, and Tcalc is the calculation result by CFD.
So in this paper, the idle speed of stator was drawn by CFD analysis and the value was nS=1175r/min.

Definition of CFD Regions Table 1.
Dimensional Specifications for CFD Model Parameters L0 H0 W0 L1 H1 W1 L H Unit m m m m m m m m Value 4 2 2 1.6 0.8 0.8 0.12 0.48 Besides, entrance boundary conditions for CFD calculating model are set to meet zero initial flow velocity and pressure, while exit boundary conditions are set as velocity and pressure gradient are zero, which can be expressed as: , (3) Other boundaries are set as symmetrical boundaries, and turbulent flow model is selected for the CFD simulation.
[6] Wang G, Shen L, Hu T, Kinematic Modeling and Dynamic Analysis of the Long-based Undulation Fin of Gymnarchus Niloticus[C], The 9th International Conference on the Simulation of Adaptive Behavior (SAB'06), Roma, Italy, 2006
Xie, Design and Simulation of the Undulate Machine Imitating the Motion of the Long Flexible Fin, Machinery Manufacturing, 2005, 43(493): 21-23
Wang etc, Simulation Platform for Fishlike Swimming, Applied Mechanics and Materials. 2013.11, 461: 451-458.

All results were obtained through 3D CFD simulations carried out with the k-omega SST model.
Curves given in [13] were compared with the current CFD results for efficiency and head.
The CFD setup and simulations Due to their accuracy in predicting the behavior of swirling flows and boundary layer separation [15], the Menter SST turbulence model [16] was chosen, with the curvature and rotation corrections [17].
Overall good correlations were observed by comparing the CFD results with the correlations from [13].
Brenner, "Unsteady CFD simulations of a pump in part load conditions using scale-adaptive simulation", International Journal of Heat and Fluid Flow Vol31, Iss 6, 2010 [5] B.Semlitsch, V.

Both methods are based on the use of CFD.
DAKOTA can select the parameters to give to the CFD simulation and can analyze the results in order to reach the optimum value desired.
In this approach, the CFD software is treated as a black-box capable of receiving input parameters and returning outputs.
The model is tested on nine new simulations, comparing the results of the CFD simulations with the predicted value of the model; the average error obtained is equal to 2.6%.
The difference with the other approach is also where the computational efforts are in the pipeline; in this case, all the simulations are run before creating the model because all the CFD simulations are used for training.

The volume of fluid (VOF) method was used for tracking of free surface in simulation program.
CFD Model Time-Averaged Flow Equations.
From Fig. 2 the CFD model predicts accurate data in comparison with experiments.
The grids used for the simulations consist of 150×61 rectangular cells.
The CFD model results exhibit well with experimental data.

Based on empirical measurements and then comparing the results with CFD simulation, the analysis exposed the distribution status of indoor hydrogen sulfide and its diffusion behavior.
The conditions of a healthier and more comfortable air environment were then obtained through CFD simulation, providing as reference to create an optimal design space for bath houses.
The correlation of the flow distribution of hydrogen sulfide with the space structure was discussed through empirical measurements and CFD simulation.
- CFD simulation Model description The indoor flow field simulation in this is study applied CFD analysis to discuss the possible patterns for flow field control at the bath site.
The relation between the variations of hydrogen sulfide concentrations with the building’s indoor space among Datun mountainous area was calculated through CFD simulation.