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The unsteady numerical simulation is carried out for the range of conditions as: Re = 1 to 30, Pr = 0.7 to100 and Ri = 0 to 1, at fixed blockage parameter β = 10%.
The simulations are carried out for Re = 5 to 40, Ri = 0 to 2 at fixed value of Pr = 1 and blockage ratio β = 25%.
(11) Numerical Procedure The numerical simulation is carried out by using the commercial CFD package ANSYS-CFX.
Fig. 2: Typical grid used for simulation.
Saghafian, Numerical Simulation of Fluid Flow and Forced Convection Heat Transfer from Tandem Circular Cylinders Using Overset Grid Method, Journal of Fluid and Structures. 28(2012) 309-327

The geometry used consists of a horizontal pipe with an elliptical cross-section of 10 m long, as illustrated in Figure 1.The geometry was developed in Autodesk Inventor Professional 2015 and, after that, exported to ICEM CFD 15.0.
(a) (b) (c) Figure 2 - Mesh used during the simulation. a) inlet; b) wall; c) outlet.
The thermo-physical properties of the fluids used in the simulation are presented in Table 1.
Table 1 - Properties of the fluids used in the simulation.
Cadé, Numerical simulation of the flow of natural gas in a cylindrical elliptical duct.

Three-dimensional steady numerical simulations have been performed in the two operation modes of low and high bypass ratio with different thermodynamic cycle parameters according to the VCE and the coolant injections have been simulated by means of additional source term method.
Figure 1.Sketch of blade profile and injection rows Computation method FINE/Turbo, a CFD package developed by NUMECA Corp. has been employed to simulate the 3D steady flows in the fully cooled turbine for the VCE.
Numerical simulations have been performed in two operation modes according to the VCE, and the coolant injections have been simulated by means of additional source term method.
A three-dimensional coupled internal/external simulation of a film-cooled turbine vane [J].
Numerical simulation of the aerodynamics performance of turbine with coolant injection [J].

In this paper, in view of three-dimensional finite element applications covered in the cylinder head, it mainly discusses the development trend both at home and abroad from the cylinder head finite element model establishment, cylinder head boundary conditions determination and cylinder head finite element computation, which application of three-dimensional finite element in study of cylinder head on temperature field simulation, the stress analysis, the machinery load and hot load, as well as the coupling analysis of multi-physical fields and multi-parts.
CHONG XIAO et al [5] took the single cylinder model as the research object, using numerical simulation method, calculated and analyzed the stress field of the cylinder head.
YU CHEN et al [12] established a three-dimensional cylinder head components model including four cylinder heads, and calculated thermal stress of the model with CFD software SC/Tetra and finite element software.
In the finite element analysis for the cylinder head of LS60MC-C Marine diesel engine, YAN FENG YANG calculated the temperature field, mechanical stress, thermal stress field of cylinder head by numerical simulation method, and then did the thermal-mechanical coupled stress field analysis.
And most of the finite element analysis of cylinder head of 3.1 ~ 3.3 doesn't take into account the contact relationship with surrounding parts, and less likely to consider multiple field at the same time, and is a series of single field and single part research method, and this kind of research method often overlooks some boundary conditions, and sets a number of assumptions, and fits correlation formula, then compares the simulation results with the actual result, finally gains the conclusion[21].

According to the structure of workbench and base of heavy hydrostatic bearing which is applied in heavy equipment, thermal deformation equations of the structure are deduced and boundary conditions for numerical simulation are established based on thermal elasticity theory.
Figure 4 shows the FE model of workbench which is generated in ICEM CFD software and it has 457643 grids totally; figure 5 shows the FE model of base which has 146943 grids totally.

Temperature profile, heat transfer coefficient and pressure profile were obtained from the simulations and the performance was discussed in terms of heat transfer rate and performance index.
The CFD domain consists of four tubes with various geometry .
The evolution of numerical simulation such as streamlines, pressure contours and isotherms for flow across a four row of tube bank with two different nanoparticle volume concentration ( water , Al2O3 ) is depicted in Fig. 2.
Conclusions Numerical simulation has been investigated on heat transfer characteristics and pressure drop of Al2O3/water nanofluid in compact heat exchanger with different tube shapes and an in-line arrangement of tubes under steady state laminar fluid flow.
Suh : Numerical Simulation of Water-Based Alumina Nanofluid in Subchannel Geometry,Science and Technology of Nuclear Installations Volume 2012, Article ID 928406, (2012) 12 pages [16] R.L.

They combined CFD and FEM coupling computing technology, and achieved abundant fruits on elastic modification of cruising appearance and aerodynamic characteristics as well as load redistribution.
Table 1 Overload, velocity pressure for gust load Loading conditions Overload (ny) Velocity pressure q/(N/m2) Lift coefficient (Cy) Load (P/N) Gust load 6.5 6385 0.72 101124 The aerodynamic load distribution was calculated by using CFD according to velocity, mach number and lift coefficient.
This is caused by the unsatisfying simulation of actual boundary conditions and poor concentrated mass distribution of the theoretical analysis model.
Unsteady Aerodynamic Simulation[M].

Analytical Approach Based on the finite volume method and the pressure-velocity coupling scheme of the SIMPLE algorithm, this study utilized the CFD software, FLUENT, to solve the three dimensional Navier-Stokes equations to analyze the velocity and pressure fields in the air gap between the partially porous aerostatic journal bearing and the spindle.
To simplify the simulation, the following assumptions were made: (1) Being restricted by the porous material, the speed of air was slow so that it was assumed to have an isotropic viscous coefficient and an invariant density.
Design Concepts and Simulation Techniques Fig. 1 Section view of an aerostatic spindle module with multiple partially porous journal bearings.
In order to have the simulation model closer to the realistic operating condition and to investigate how the quantity of the porous insert affected the gap pressure, a design including two partially porous journal bearings separated by 54 mm and three air outlets was made, as shown in Fig. 4, for analysis of the gap pressure.
Rao, Simulation based on FLUENT and experimental research of porous aerostatic bearing, Master Thesis, School of Mechatronics Engineering, Harbin Inst. of Tech., China, 2006

Numerical simulations wereperformedto analyze the airflow in the subway twin-track tunnel [5, 6].
The choice of the turbulence model depends on considerations such as the flow physics including massive flow separations, established practice of a specific class of problem, level of accuracy required, available computational resources, and amount of computing time available for the simulation.
References [1] Jeon, J.S., Seo, J.W., Jeon, M.J., Eom, S.W., and Chae Y.Z., 2012, “Indoor Radon levels in the subway cabins of the Seoul metropolitan area”, Journal of Korean Society for Atmospheric Environment, Vol.28. pp. 374-383 (in korean) [2] Modic, J., 2003, “Fire simulation in road tunnels”, Tunnelling and Underground Space Technology”, vol. 18, pp 525-530 [3] Ogawa, T., and Fujii, K., 1997, “Numerical investigation of three-dimensional compressible flows induced by a train moving into a tunnel, Computers & Fluids, vol. 26, pp 565-585 [4] Chen, T.Y., Lee, Y.T., and Hsu, C.C., 1998, “Investigations of piston-effect and jet fan-effect in model vehicle tunnels”, Journal of Wind Engineering and Industrial Aerodynamics, vol.73, pp 99-110 [5] Li, J., Peng, H., and Li S.J., 2006, “Numerical simulation of flow characteristics in bidirectional subway tunnel”, Journal of Thermal Science and Technology, vol. 5, pp 331-334 [6] Waymel, F., Monnoyer, F., and William-Louis, M.J.P., 2006,
“Numerical simulation of the unsteady three-dimensional flow in confined domains crossed by moving bodies”, Computers & Fluids, vol.35, pp 525-543 [7] Karlsson, H.
” Asian Journal of Atmospheric Environment, vol.2-1, pp. 60-67 [9] ANSYS CFX, 2009, ANSYS Workbench, ICEM-CFD, CFX-Pre, CFX-Solver, CFX-Post User’s Manual

Scheme of the object taken to numerical calculations: a) mesh, b) boundary conditions Numerical simulations were carried out by means of Volume of Fluid model (1 phase - water, 2 phase – argon).
Convergence of results obtained from two different methods confirms the choice of VOF model for numerical simulation and also that the assumptions were made properly.
The next step of research should focus on numerical simulation for three-dimensional case.
Pfeifer, Numerical and physical simulation of tundish fluid flow phenomena, Steel Research 74 (2003) 44-55
Jolly, Study of molten aluminium cleaning process using physical modelling and CFD, Light Metals TMS (2004) 743-748