Construction of Full Way Coupling LES for Particle-laden Turbulent Flows Using Dynamic SGS Models.

康斌, 雷; 伸行, 谷口; 敏雄, 小林

doi:10.1299/kikaib.68.352

Cited by 5 publications

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“…The wall friction is estimated by the product of the velocity gradient and the eddy viscosity. The SGS energy is estimated by the following equations [22]: The result of case 1 converges at 0.75 s and fluctuates around w D 1.0 Pa.…”

Section: Resultsmentioning

confidence: 99%

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Large eddy simulation and a simple wall model for turbulent flow calculation by a particle method

Arai

Koshizuka

Murozono³

2012

Numerical Methods in Fluids

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SUMMARY A turbulent channel flow and the flow around a cubic obstacle are calculated by the moving particle semi‐implicit method with the subparticle‐scale turbulent model and a wall model, which is based on the zero equation RANS (Reynolds Averaged Navier‐Stokes). The wall model is useful in practical problems that often involve high Reynolds numbers and wall turbulence, because it is difficult to keep high resolution in the near‐wall region in particle simulation. A turbulent channel flow is calculated by the present method to validate our wall model. The mean velocity distribution agrees with the log‐law velocity profile near the wall. Statistical values are also the same order and tendency as experimental results with emulating viscous layer by the wall model. We also investigated the influence of numerical oscillations on turbulence analysis in using the moving particle semi‐implicit method. Finally, the turbulent flow around a cubic obstacle is calculated by the present method to demonstrate capability of calculating practical turbulent flows. Three characteristic eddies appear in front of, over, and in the back of the cube both in our calculation and the experimental result that was obtained by Martinuzzi and Tropea. Mean velocity and turbulent intensity profiles are predicted in the same order and have similar tendency as the experimental result. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

“…The RMS values are calculated by the following equation: Root mean squares taking into account the SGS energy is also shown in Figure 6. The SGS energy is estimated by the following equations [22]:…”

Section: Resultsmentioning

confidence: 99%

Large eddy simulation and a simple wall model for turbulent flow calculation by a particle method

Arai

Koshizuka

Murozono³

2012

Numerical Methods in Fluids

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“…On the other hand, Large-Eddy Simulation (LES) achieved good prediction for turbulent unsteady flow field, e.g., Ref. (3), particle laden flows (4), (5) , turbulent combustion flows (6), (7) , and turbulent flow with vaporizing spray droplets (8) .…”

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

Numerical Study on Liquid Fuel Spray Behavior in Turbulent Flames Using LES

Itoh

Oshima

2009

JTST

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In the present study, Large-Eddy Simulation (LES) modeling for turbulent spray combustion flows has been developed in conjunction with the Eulerian/Lagrangian method for the gas phase and dispersed phase representation and flamelet approach for combustion modeling. Moreover, a new thermal energy coupling model is proposed to estimate the thermal interaction between the gas phase and the dispersed phase. The governing equations for the gas phase are the mass and momentum conservation equations and the mixture fraction transport equation. The governing equations for spray droplets are the mass, momentum, and thermal energy equations for each droplet. We applied the numerical procedure to a laboratory-sized spray combustor and found that procedure can predict key features of turbulent spray combustion phenomena, such as the temperature distribution of the combustion gas, individual droplet behavior, and droplet vaporization phenomena. Moreover, the flame temperature drop caused by the thermal impact from the spray droplets is expressed properly by employing the coupling model.

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“…A random walk model (6) is applied to consider the contribution of SGS velocity to the particle motion, which was about 5% at a later stage of the injection.…”

Section: Governing Equationsmentioning

confidence: 99%

“…Although LES involves higher computational costs than RANS, this is not a major disadvantage because of the rapid computer performance growth in the recent years. Lei et al (6) calculated particle-laden channel flows and suggested particles aggregated into the low vorticity areas. Hori et al (7) applied LES to inject diesel spray into a static field.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Spray Injection to Turbulent Flows from a Slit Nozzle

Arai

Oshima

et al. 2007

JFST

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Slit nozzles are used in some gasoline direct injection engines and makes fan shaped spray. Spray injecting flows to turbulent flows from a slit nozzle have been analyzed numerically using combination of Large Eddy Simulation (LES) and lagrangian Discrete Droplet Method (DDM). As a result, LES can resolve the internal structure of the spray and irregular droplet distribution made by small eddies that momentum of spray itself induced. In conventional Reynolds Averaged Navier-Stokes (RANS) combined DDM calculation such eddies cannot be resolved, and also the internal spray structure or irregularity doesn't appear since all effects of turbulence are averaged. But such structure or irregularity is important for stable combustion in gasoline direct injection engines. Therefore the combination of LES and DDM method will play essential role for developing more robust and high efficient engines under wide operating conditions. We also proposed the way of constructing pseudo particle image in order to compare calculation results with sliced spray pictures obtained by experiments. We show time changes of the shape of brightness Probability Density Function (PDF) can be used to evaluate variance of spray droplets.

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Construction of Full Way Coupling LES for Particle-laden Turbulent Flows Using Dynamic SGS Models.

Cited by 5 publications

References 0 publications

Large eddy simulation and a simple wall model for turbulent flow calculation by a particle method

Large eddy simulation and a simple wall model for turbulent flow calculation by a particle method

Numerical Study on Liquid Fuel Spray Behavior in Turbulent Flames Using LES

Large Eddy Simulation of Spray Injection to Turbulent Flows from a Slit Nozzle

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