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A New Inlet Boundary Conditon For LES Zhe Liu Department of Civil Engineering, Shantou University, Guangdong Province, 515063, P.R.CHINA liuzhe@stu.edu.cn Keywords: LES, ARMA, CFD Abstract.
It is known that the inlet boundary condition is still a problem for tubulence simulation.
Introduction The generation of velocity fluctuations for the unsteady inlet boundary condition is one of the important unresolved issues in CFD research.
The standard and dynamic LES models are adopted to compare the simulation results.
The simulation time step is 0.01s.

Computational fluid dynamics (CFD) was employed to numerically calculate the air flow field.
Then, the numerical simulation study was carried out with the well-known CFD soft—FLUENT to obtain the load carrying capacity, stiffness and pressure distribution in the bearing clearance.
Table 1 Parameters of different restrictors Case Bearing code Restrictor type Supply hole diameter [mm] Supply hole height [mm] Spaceing distance between supple holes [mm] 1 1X0.30 Single hole 0.30 0.35 0 2 4X0.15 2X2 four holes 0.15 0.35 0.4 3 9X0.10 3X3 nine holes 0.10 0.35 0.3 Governing Equations of CFD Simulation and the Boundary Conditions Governing Equations.
Simulation Results and Discussions Validity of the Numerical Simulation.
Fig.3 Comparison of CFD results with experimental data in [9].

Both the numerical and the experiment results show that the critical flow rate decreases with the increasing annular gap, and the simulation results correspond well with experimental results.
The FLUENT, as the most comprehensive function, the most widely applicability and the popular CFD software package, has been widely used in the aerospace, oil and gas, turbine design etc [6].
Numerical simulation methods The commercial CFD software FLUENT was employed in the study.
Also, the experimental platform was set up to verify the correctness of simulation results.
Wang: Computational Fluid Dynamics Analysis-CFD Software Theory Application (Tsinghua University Press, China 2004).

In order to capture details of transient turbulent flow, large eddy simulation (LES) is employed.
CFD Methodology.
In this study, the computational fluid dynamics (CFD) software ANSYS-Fluent is employed, and particularly, the large eddy simulation (LES) method is used to capture the transient turbulent flow field.
The air used in the simulation is assumed to obey the ideal gas law.
In order to justify our CFD model, the existing experiment data [7] on pressure distribution in an aerostatic bearing are utilized for comparison.

This paper presents numerical simulation of the vortex flow field with anisotropy turbulence in cyclone dust collector using modified K-ε model and IMPLE algorithm.
References [1] Hou zhiqiang et al., CFD analysis on air flow field in ordinary cyclone, Journal of mining machinery. 38:15 (2010) 106-109
[4] Chen Yanbai et al., Numerical simulation of three-dimensional flow field in cyclone separators, Applied Energy Technology, 173 (2012) 46-50
[5] Zhang Bo, Wen Jianjun, Simulation and analysis on flow field of cyclone separator, Computer Aided Engineering, 20:2 (2011) 100-103
[6] Hou Xiaohong, Chen Wenyi, Numerical analysis of flow field in a cyclone dust separator based on DPM-CFD, Journal of mining machinery, 40:6 (2012) 93-97.

Cold Gas Dynamic Spray Technology: The Simulation of Aerodynamics of Flow Liang Cui, Andrew G.
CFD as a method has a deep root in explaining physical phenomenon through model development/simulation across a range of fields from aerospace, turbomachinery, multi-phase flow and heat transfer, to microflows, environmental flows, and fluid-structure interaction problems [4].
Computational Domain and Boundary Conditions The CFD computational nozzle meshing grid is displayed in fig. 3.
Developed meshing for fluid and solid domains: CFD computational grid.
Numerical Results and Discussion Fig. 4 displays the CFD results with an emphasis on capturing expected aerodynamic behavior.

With the rapidly development of CFD technology and computer technic, results of CFD calculations can provide us with plenty of reference[3-5].So it’s a kind of labour and time saving to use CFD method in the hydraulic model research of nuclear main pump, by which we can screen the designed model accordingly.
The whole domain flow channel was assembled in PRO/E and imported to ICEM-CFD for grid partition.
The numerical simulation adopted three-dimensional steady incompressible time average Reynolds equations, which was closed with standard k-ε turbulent model.The specific mathematical model refer to references.
Nuclear Engineering and Design, Vol. 167 (1996), p.91 [3] Zhijiang Wu,WanYong Zhao: Numerical simulation of interior flow field of mixing flow pump[J].Fluid Machinery, Vol. 33-10 (2005), p. 15.
:Numerical simulation of the effect of structure parameters on the mixing circulating water pump performance[J].

Took a typical soil-walled passive greenhouse located in Jinan, Shandong, China as an example, an unsteady tri-dimensional numerical simulation was applied to solve the temperature and humidity profiles under natural ventilation conditions inside the greenhouse, based on the CFD program.
The simulation results agree well with test values about the temperature and humidity inside the greenhouse with fitting degree of 99.8% and 99.7%, respectively.
With the development of computer technology, computational fluid dynamics (CFD) software becomes a powerful tool to study the spatial distribution of thermal and moisture environment in greenhouse.
The simulation results and the experimental data of greenhouse operating parameters which include the indoor air temperatures as well as the RH are compared for validation, as shown in Figures 1 and 2.
Lee, “3-D CFD analysis of relative humidity distribution in greenhouse with a fog cooling system and refrigerative dehumidifiers”, Biosysrems Engineering, Vol. 100, issue 2, 245-255, 2008 [3] Boulard, T. and S.

To evaluate the interlaced chord network and the proposed velocity field reconstruction algorithm, numerical simulation experiments were conducted with theoretical profiles and computational fluid dynamics (CFD) models of typical flow regimes.
In numerical simulation experiments, the actual measurement of chord velocities is substituted by interpolation of point velocities along the chords in the CFD models and the theoretical profiles.
The CFD simulation was performed by the software ANSYS CFX.
The reconstructed velocity field can well approximate the CFD simulation result when N=13 transducers are utilized.
(a) CFD simulation result.

Based on this optimized geometry, the aim of the present paper was to verify the influence of the underflow diameter on the overall separation process at 147 kPa on the same optimized hydrocyclone geometry, but without the filtration effect, by performing laboratory experiments and CFD simulations using the commercial software Fluent®.
For that reason, CFD was applied in this study.
In order to understand better the internal flow of the equipment, the volumetric feed flow rate results shown in Table 1 were used as input for the fluid dynamic simulations.
Fig. 2 and 3 show the final results of these simulations.
vz(m/s) DU (mm) 3 4 5 Fig. 2 – CFD results of descendent axial velocity (vz).