Near-Wall Modeling of Plane Turbulent Wall Jets

1997 ◽  
Vol 119 (2) ◽  
pp. 304-313 ◽  
Author(s):  
G. Gerodimos ◽  
R. M. C. So
Keyword(s):  
Boundary Layer ◽  
Outer Region ◽  
Plane Wall ◽  
Equation Modeling ◽  
Wall Jets ◽  
Free Jet ◽  
Turbulent Wall Jets ◽  
Turbulent Wall ◽  
Simple Flows ◽  
Near Wall

In most two-dimensional simple turbulent flows, the location of zero shear usually coincides with that of vanishing mean velocity gradient. However, such is not the case for plane turbulent wall jets. This could be due to the fact that the driving potential is the jet exit momentum, which gives rise to an outer region that resembles a free jet and an inner layer that is similar to a boundary layer. The interaction of a free-jet like flow with a boundary-layer type flow distinguishes the plane wall jet from other simple flows. Consequently, in the past, two-equation turbulence models are seldom able to predict the jet spread correctly. The present study investigates the appropriateness of two-equation modeling; particularly the importance of near-wall modeling and the validity of the equilibrium turbulence assumption. An improved near-wall model and three others are analyzed and their predictions are compared with recent measurements of plane wall jets. The jet spread is calculated correctly by the improved model, which is able to replicate the mixing behavior between the outer jet-like and inner wall layer and is asymptotically consistent. Good agreement with other measured quantities is also obtained. However, other near-wall models tested are also capable of reproducing the Reynolds-number effects of plane wall jets, but their predictions of the jet spread are incorrect.

Heat Transfer to Plane Turbulent Wall Jets

1963 ◽  
Vol 85 (3) ◽  
pp. 209-213 ◽  
Author(s):  
G. E. Myers ◽  
J. J. Schauer ◽  
R. H. Eustis
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Temperature Distribution ◽  
Wall Jet ◽  
Analytical Prediction ◽  
Two Dimensional ◽  
Heat Transfer Characteristics ◽  
Wall Jets ◽  
Turbulent Wall Jets ◽  
Turbulent Wall

The heat-transfer characteristics of two-dimensional, incompressible, turbulent wall jets are discussed. An analytical prediction is made for the local Stanton number and data are presented for a step wall temperature distribution. The method for extending these data to arbitrary heating conditions is shown. Temperature surveys in the wall jet boundary layer are also presented.

scholarly journals Curvature Effects on Two-dimensional Turbulent Wall Jets along Concave Surfaces

1983 ◽  
Vol 26 (222) ◽  
pp. 2074-2080 ◽  
Author(s):  
Ryoji KOBAYASHI ◽  
Nobuyuki FUJISAWA
Keyword(s):  
Two Dimensional ◽  
Wall Jets ◽  
Curvature Effects ◽  
Turbulent Wall Jets ◽  
Turbulent Wall

Erosion By Circular Turbulent Wall Jets

1977 ◽  
Vol 15 (3) ◽  
pp. 277-289 ◽  
Author(s):  
N. Rajaratnam ◽  
B. Berry
Keyword(s):  
Wall Jets ◽  
Turbulent Wall Jets ◽  
Turbulent Wall

Instability in a viscous flow driven by streamwise vortices

2001 ◽  
Vol 432 ◽  
pp. 127-166 ◽  
Author(s):  
K. W. BRINCKMAN ◽  
J. D. A. WALKER
Keyword(s):  
Boundary Layer ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Wall Layer ◽  
External Flow ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Wall Flow ◽  
Turbulent Wall ◽  
Near Wall

Unsteady separation processes at large finite, Reynolds number, Re, are considered, as well as the possible relation to existing descriptions of boundary-layer separation in the limit Re → ∞. The model problem is a fundamental vortex-driven three-dimensional flow, believed to be relevant to bursting near the wall in a turbulent boundary layer. Bursting is known to be associated with streamwise vortex motion, but the vortex/wall interactions that drive the near-wall flow toward breakdown have not yet been fully identified. Here, a simulation of symmetric counter-rotating vortices is used to assess the influence of sustained pumping action on the development of a viscous wall layer. The calculated solutions describe a three-dimensional flow at finite Re that is independent of the streamwise coordinate and consists of a crossflow plane motion, with a developing streamwise flow. The unsteady problem is constructed to mimic a typical cycle in turbulent wall layers and numerical solutions are obtained over a range of Re. Recirculating eddies develop rapidly in the near-wall flow, but these eddies are eventually bisected by alleyways which open up from the external flow region to the wall. At sufficiently high Re, an oscillation was found to develop in the streamwise vorticity field near the alleyways with a concurrent evolution of a local spiky behaviour in the wall shear. Above a critical value of Re, the oscillation grows rapidly in amplitude and eventually penetrates the external flow field, suggesting the onset of an unstable wall-layer breakdown. Local zones of severely retarded streamwise velocity are computed which are reminiscent of the low-speed streaks commonly observed in turbulent boundary layers. A number of other features also bear a resemblance to observed coherent structure in the turbulent wall layer.

Scour by jets in cohesionless and cohesive soils

2007 ◽  
Vol 34 (6) ◽  
pp. 744-751 ◽  
Author(s):  
Kerry A Mazurek ◽  
Tanvir Hossain
Keyword(s):  
Impinging Jets ◽  
Coarse Grained ◽  
Cohesive Soils ◽  
Wall Jets ◽  
Fine Grained ◽  
Water Jets ◽  
Turbulent Wall Jets ◽  
Turbulent Wall ◽  
Turbulent Water ◽  
Unified Method

A technique is developed in this paper to unify the methods of analyzing scour by turbulent water jets in cohesionless and cohesive soils. Data from previous studies using circular turbulent impinging jets and circular turbulent wall jets are used to compare the scour in low void ratio cohesive soils to that in uniform sands and gravels. Scour by these jets is related to the dimensionless excess stress on the soil bed. It is seen that this parameter will likely work well for developing a method to predict scour for circular wall jets that is applicable to both materials. However, a circular impinging jet appears to vary appreciably in its interaction with the bed between the two types of soil, which makes developing a unified method to predict scour by impinging jets more difficult. Key words: erosion, scour, water jets, cohesionless sediments, cohesive sediments, fine-grained soils, coarse-grained soils.

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