Numerical investigation of forced turbulent wall jets

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.

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The interaction of two opposing plane turbulent wall jets

10.2514/6.1972-211 ◽

1972 ◽

Cited By ~ 10

Author(s):

R. KIND

Keyword(s):

Wall Jets ◽

Turbulent Wall Jets ◽

Turbulent Wall

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Scour by jets in cohesionless and cohesive soils

Canadian Journal of Civil Engineering ◽

10.1139/l07-005 ◽

2007 ◽

Vol 34 (6) ◽

pp. 744-751 ◽

Cited By ~ 14

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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