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LARGE EDDY SIMULATION OF THE INTERACTION BETWEEN wall jet AND OFFSET jet

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Journal of Hydrodynamics 2011年第5期23卷 544-553页

作者： LI Zhi-wei HUAI Wen-xin HAN Jie State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan 430072 China

The interaction between a plane wall jet and a parallel offset jet is studied through the Large Eddy Simulation （LES）. In order to compare with the related experimental data, the offset ratio is set to be 1.0 and the Reynolds number Re is 1.0× 104 with respect to the jet height L and the exit velocity U0. The Finite Volume Method （FVM） with orthogonal-mesh （6.17× 106 nodes） is used to discretize governing equations. The large eddies are obtained directly, while the small eddies are simulated by using the Dynamic Smagorinsky-Lily Model （DSLM） and the Dynamic Kinetic energy Subgrid-scale Model （DKSM）. Comparisons between computational results and experimental data show that the DKSM is especially effective in predicting the mean stream-wise velocity, the half-width of the velocity and the decay of the maximum velocity. The variations of the mean stream-wise velocity and the turbulent intensity at several positions are also obtained, and their distributions agree well with the measurements. The further analysis of dilute characteristics focuses on the tracer concentration, such as the distributions of the concentration （i.e., C / C0 or C / C,,）, the boundary layer thickness 6c and the half-width of the concentration b., the decay of the maximum concentration （ C / Co） along the downstream direction. The turbulence mechanism is also analyzed in some aspects, such as the coherent structure, the correlation function and the Probability Density Function （PDF） of the fluctuating velocity. The results show that the interaction between the two jets is strong near the jet exit and they are fully merged after a certain distance.

关键词： wall jet offset jet dilute characteristic coherent structure

Variation of Transition Characteristics in a wall jet

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Journal of Thermal Science 2003年第2期12卷 167-170页

作者： Marie-Francoise Scibilia Centre National de la Recherche Scientifique ParisFrance

The characteristics of a laminar wall jet submitted to different configurations have been experimentally explored in order to obtain a better knowledge of transition modifications,In fact different parameters can accelerate or delay the transition using a smooth or rough surface,heated or not,submitted to vibrations or not .In this study,significant effects can be *** has been possible to measure the beginning of growth rates of disturbance amplitude using a wind tunnel and comparing the results with the linear stability theory.

关键词： wall jet transition acoustic vibration heat transfer turbulence roughness.

Heat Transfer in a Forced wall jet on a Heated Rough Surface

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Journal of Thermal Science 2000年第1期9卷 85-92页

作者： Marie-Francoise Scibilia Lemfi - Centre National de la Recherche Scientifique Campus Universitaire

In this paper, an experimental investigation of a Iaminar wall jet in the presence of a heated wall with stationary particles on its surface, is reported. The wall jet was submitted to external acoustic vibrations amplifying the coherent structures appearing in the laminar region. A wind tunnel was used at very low Reynolds number. Mean velocity and turbulence intensity were measured by a constant temperature anemometer. Measurements were taken in the transition and turbulent regions. Embedded particles were outside the viscous sublayer and it was observed that their presence modifies significantly the flow characteristics in particular the boundary layer is thickened. This study can bring a better understanding of the structure of a flow when it is heated and forced on a rough wall.

关键词： heat transfer turbulence boundary layer wall jet roughness acoustics.

Effect of wall jet on the bubble dynamics near arigid wall

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排灌机械工程学报 2017年第6期35卷 467-471页

作者： LU Jie QIAN Zhongdong GUO Zhiwei WANG Chihang SU Jiahui State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University

The bubble dynamic near a rigid wall with a wall jet was investigated by codynamics(CFD)method with the volume of fluid(VOF)model,which had been validated by vious experimental *** effects of different velocities of the wall jet and ditances on the bubble dynamics were *** results show that the bubble is squjet due to more force added on the *** the velocity of the wall jet increa,the wall anthe pressure along the wall at collapse time increase because of the extra push indAs the stand-off distance increases,the pressure along the wall first increases then decrethe distance from the bubble to the wall increases.

关键词： bubble dynamic wall jet volume of fluid computational fluid dynamics(CFD)

Experimental Study of the Diffusion of a Confined wall jet through a Perforated Plate: Influence of the Porosity and the Geometry

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Open Journal of Fluid Dynamics 2022年第1期12卷 96-126页

作者： Moussa Diop Denis Flick Graciela Alvarez Jean Moureh Refrigerating Process Engineering Unit INRAE Antony Antony France UMR SayFood AgroParisTech INRAE Université Paris Saclay Massy France

This paper investigated lateral diffusion of a confined two-dimensional wall jet (air inlet height: 5 cm) through a perforated plate. We considered two plates with porosities of and . The plates were positioned at distances of 10 cm and 20 cm below the jet inlet. The experiments were realized using 2D Laser Doppler Anemometer (LDA). Different profiles of mean and fluctuating velocities are presented. The presence of a perforated plate strongly modified the airflow pattern compared to an empty enclosure. The velocities above and below the plate depend on several parameters, including the porosity and the plate’s position relative to the inlet slot and the longitudinal position. The difference between the flow velocity above and below the plates could not be related using a universal formula that depends on these parameters. We also investigated the influence of a porous media of a height of 20 cm (a stack of spheres having a diameter of 3.75 cm) located below the perforated plate. The results highlight that the porous medium strengthens the effects of the perforated plate on the flow.

关键词： Porous Medium Perforated Plate wall jet Air Ventilation Aeraulic Turbulence Diffusion

Experimental and Numerical Investigation of the Diffusion of a Confined wall jet through a Perforated Plate

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Open Journal of Fluid Dynamics 2022年第2期12卷 168-212页

作者： Moussa Diop Denis Flick Graciela Alvarez Jean Moureh Refrigerating Process Engineering Unit INRAE Antony Antony France Université Paris Saclay INRAE AgroParisTech UMR SayFood Massy France

When performing numerical modeling of fluid flows where a clear medium is adjacent to a porous medium, a degree of difficulty related to the condition at the interface between the two media, where slip velocity exists, is encountered. A similar situation can be found when a jet flow interacts with a perforated plate. The numerical modeling of a perforated plate by meshing in detail each hole is most often impossible in a practical case (many holes with different shapes). Therefore, perforated plates are often modeled as porous zones with a simplified hypothesis based on pressure losses related to the normal flow through the plate. Nevertheless, previous investigations of flow over permeable walls highlight the impossibility of deducing a universal analytical law governing the slip velocity coefficient since the latter depends on many parameters such as the Reynolds number, porosity, interface structure, design of perforations, and flow direction. This makes the modeling of such a configuration difficult. The present study proposes an original numerical interface law for a perforated plate. It is used to model the turbulent jet flow interacting with a perforated plate considered as a fictitious porous medium without a detailed description of the perforations. It considers the normal and tangential effects of the flow over the plate. Validation of the model is realized through comparison with experimental data.

关键词： Perforated Plate Porous Medium wall jet Air Ventilation Aeraulic Turbulence Diffusion

Critical Heat Flux in Forced Convective Boiling with a wall jet

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Transactions of Tianjin University 2004年第1期10卷 63-66页

作者：王迅 School of Mechanical Engineering Tianjin University

The critical heat flux (CHF) in the forced convective boiling with a wall jet has been *** experiments of CHF with a wall jet have been performed over a wide range of ρ l/ρ g=6.6-1 603 and ΔT sub =0-60 K. The mechanism on CHF is discussed and a CHF model based on heat balance in sublayer can provide a good clue for analyzing and deriving ***,a generalized correlation is presented, which can predict CHF for saturated and subcooled conditions.

关键词： critical heat flux wall jet saturated liquid subcooled liquid

Numerical and experimental study of Boussinesq wall horizontal turbulent jet of fresh water in a static homogeneous environment of salt water

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Journal of Hydrodynamics 2015年第4期27卷 604-615页

作者： BELCAID Aicha LE PALEC Georges DRAOUI Abdeslam IUSTI Laboratory UMR 7343Aix-Marseille UniversitéTechnopole de Chateau-Gombert5 rue Enrico Fermi13453 Marseille Cedex13France Energy Laboratory Research in Energy and Thermal Transfer TeamAbdelmalek Essaadi UniversityFaculty of Sciences and TechniquesTangierMorocco

This paper investigates a numerical and experimental study about buoyant wall turbulent jet in a static homogeneous environment. A light fluid of fresh water is injected horizontally and tangentially to a plane wall into homogenous salt water ambient. This later is given with different values of salinity and the initial fractional density is small, so the applicability of the Boussinesq approximation is valid. Since the domain temperature is assumed to be constant, the density of the mixture is a function of the salt concentration only. Mathematical model is based on the finite volume method and reports on an application of standard k- ？ turbulence model for steady flow with densimetric Froude numbers of 1-75 and Reynolds numbers of 2 000-6 000. The basic features of the model are the conservation of mass, momentum and concentration. The boundaries of jet body, the radius and cling length are determined. It is found that the jet spreading and behavior depend on the ratio between initial buoyancy flux and momentum, i.e., initial Froude number, and on the influence of wall boundary which corresponds to Coanda effect. Laboratory experiments were conducted with photographic observations of jet trajectories and numerical results are described and compared with the experiments. A good agreement with numerical and experimental results has been achieved.

关键词： wall jet turbulence Boussinesq approximation k-? model buoyancy cling length

NUMERICAL INVESTIGATION OF TURBULENT COUNTER-GRADIENT-TRANSPORT IN ASYMMETRIC FLOW WITH A jet

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Journal of Hydrodynamics 2004年第2期16卷 115-123页

作者： QIUXiang GUOHui-fen LIUYu-lu ShanghaiInstituteofAppliedMathematicsandMechanics ShanghaiUniversityShanghai200072Chinae-mailylliu@yc***

By using the Reynolds Stress Closure Model (RSM), turbulentCounter-Gradient-Transport (CGT) phenomenon was numerically investigated in asymmetric flow with ajet, and the computational results were compared with experimental data. The computational resultsshow that the negative turbulent energy production only appears at some certain stations in CGTregion, this fact indicates that the CGT phenomenon exists more widely than the negative turbulentenergy production; while the CGT region exists all along, it gradually shrinks in the favorablepressure gradient zone until the position of the wing central part is reached, where it vanishes,but it appears in the adverse pressure gradient region; in addition, the location in the flow whereuv = 0 switched sides, relative to where partial deriv U/partial deriv y = 0, from favorablepressure gradient to adverse pressure gradient. The pressure gradient takes an important effect onthe region of negative turbulent energy production and CGT.

关键词： counter-gradient transport (CGT) reynolds stress model (RSM) wall jet pressure gradient