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Investigation of Drag Reduction due to Dimpled Surfaces in Narrow Channels by Means of Flow Simulations Julian Praß1,a*, Jörg Franke2,b and Stefan Becker1,c 1Institute of Processmachinery and Systems Engineering, Cauerstraße 4, 91058 Erlangen, Germany 2Institute for Factory Automation and Production Systems, Egerlandstraße 7-9, 91058 Erlangen, Germany apr@ipat.uni-erlangen.de, bjoerg.franke@faps.fau.de, csb@ipat.uni-erlangen.de *corresponding author Keywords: CFD, RANS, Dimples, Drag Reduction Abstract.
All geometries were studied under two different flow conditions ReH ≈ 2 430 and ReH ≈ 4 860 using Reynolds averaged Navier-Stokes equations (RANS) within the commercial computational fluid dynamics (CFD) code ANSYS CFX®.
For this reason, the simulations were run until residuals fell below 10−6.
Afterwards, the average pressure difference ∆P was calculated from the last 300 iterations of each simulation which was uses as new boundary condition for a second simulation on the corresponding geometry.
This result proves the suitability of the meshes used for the simulations of dimpled walls.

The muffler attenuation performance of work is directly related to noise size of vehicle, it relates to environmental pollution[5].In this paper presence problem of exhaust muffler is analyzed, using three three-dimension fluid numerical calculation(CFD) tool velocity and pressure distribution are performed, and sound field also calculated, after improvement experiment is certificated .
Then after exported into computational fluid dynamics (CFD) software flow field simulation is analyzed.
Due to the steady-state condition is equal to the simulation of initial conditions boundary condition, so boundary conditions can be input.
Conclusions Through the above CFD and acoustic field numerical calculation of a vehicle exhaust silencer analysis and calculation, we can get conclusions that in the range of the analyzing speed the insertion loss of 28dB (A) standard is satisfied firstly, and in care of frequency band, set-net tail pipe noise is about small 5 dB (A) than target, secondly compared with the original muffler 7.6 kPa, pressure loss is dropped about 32%.

The main objective of this analysis is to evaluate the heat-shielding effects of design layout and operating parameters of helium cooling-pipes with cfd (computational fluid dynamics) techniques.
The main objective of this analysis is to evaluate the effects of ctb thermal shield in design layout and operating parameters of helium cooling pipes with cfd (computational fluid dynamics) techniques.
Therefore the reynolds averaged navier-stokes (rans) equations, in combination with shear-stress transport (sst) turbulence models are used for this cfd analysis.
For solid region, the following 3dimension heat conduction equations are used: (7) CFD Computational Models and Mesh Arrangement A full size model of ctb ts is considered in the cfd study as shown in Fig.3.
(2) An ideal contact (0 contact heat resistance) between panels and helium cooling pipes is assumed in this simulation.

According to the results of simulation, we investigated the different radiant heat flux parameters, burning losses under different heat release rates and rising rates.
Also, we compared the simulation results with the actual smoke trace and burning rates in fire accidents.
The numeric simulation test in this article applies the FDS [2-4] (Fire Dynamics Simulator, Fire dynamics simulation) software which developed by USA NIST.
FDS is a CFD model calculates the flowing fire driven fluid.
[5] Fu-Jun Wang, Computational Fluid Dynamics Analysis -CFD Software Principle and Application [M].

In addition, along with the rapid development of computer technology and numerical method,numerical simulation becomes a powerful method to study cavitation phenomenon. cavitating flow field was simulated based computational fluid dynamics (CFD) and so on[5,6,7,8].
The numerical simulation was used to simulate the flow field around the hydrofoil.
Hydrofoil model Numerical simulation The flowing fluid media in the model is water, the flow is single-phase flow, so liquid flow in the model can be considered as incompressible flow.
For presented simulation, unstructured tetrahedral mesh, shown in figure 2, is used in the computational domain.
Conclusions The present work demonstrates the possibility of using CFD in improving cavitation phenomenon in hydraulic machine.

Finally, steady flow simulations are performed using the CFD solver Fluent.
Introduction Blood flow simulations are helpful in understanding certain phenomena, such as the perfusion of the cardiac pump.
Once adequately meshed, blood flow simulations have been carried out.
Figure.1 Geometrical model and mesh Figure.2 Domain mesh with references Simulation The flow in our model was computed using the software Fluent.

Ltd, Shanghai, China Keywords: regenerative furnace, switching model, flow character, numerical simulation; Abstract.
So, on the basis of analyzing the burning and heat transfer mechanism, the physical and mathematical model of the heating section was built and the CFD was used to research the influence of four classical switching models on the flow profile.
Numerical simulation method Gambit 2.3 was applied to build the geometry model and mesh it.
Numerical simulation of the combustion[M].Beijing: Science Press, 1986
Numerical Simulation on the Effect of Switching Modes on the Thermal Process of a HTAC Reheating Furnac[J].

Applying commercial CFD software FLUENT, the cavitation issuing from the orifice was numerically investigated, reducing the harm.
Because of complicated flow field and high-cost experiment, it is important to predict cavitation erosion by numerical technology such as CFD.
In addition, the effect of surface tension weaker than viscosity, compared from the Fig. 3 and Fig. 2. ——0.1 ------0.5 …….0.8 Fig.3 Time evolution of the bubble radius R(t) in liquids of different surface tension. 3.3 effect of temperature on cavitation bubbles The numerical simulations of radius evolution, R, versus t are shown in Fig. 4, which are obtained from Equation (7).
Meehanical Engineering Science.2009,223(C10):2297-2307 [2] Liu Xiaohong,Ke Jian.Noise Appraisement of Hydraulic Poppet Valve Based on CFD Analysis[J].
Three-dimensional CFD study of liquid-solid flow behaviors in tubular loop polymerization reactors：The effect of guide vane［J］.

To investigate the mixing uniformity between tracer gas and gas stream in the duct, numerical simulations of the CO tracer gas and air mixing in a 300mm diameter and 90 degree elbow duct were performed on the commercial CFD software FLUENT, and the comparisons between the simulation results and experimental data were analyzed.
The results indicated that the tracer gas concentrations of simulations were agreed with the experimental data.
Experimental set-up and numerical simulations Experimental set-up.
The simulation results are showed good agreement with the experimental results.
The simulation results were in good agreement with the experimental data.

As recent studies, fluid flow characteristics in the diffuser-type shrouds of power generation system which is operated by river flow were analyzed, and the turbine efficiency was predicted with the momentum source factors through CFD [1, 2].
Therefore, in this study, flow field characteristics for seawater in various tidal current directions are investigated with numerical simulation which presents the angular velocity and drag force of turbine system. 1.
Numerical modeling In this study, commercial CFD code (Fluent 6.3) is used for the numerical analysis.
Conclusion In this study, numerical analysis by CFD has been performed to investigate seawater flow characteristics and drag force changes in tidal current turbine system with the variation of current direction.
Song, Fundamental study on the HAT(Horizontal Axis Turbine) tidal current power rotor performance by CFD, The Korean Society for New and Renewable Energy. 5 (2009) 3-7.