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In this paper measurements are presented of mean velocities, turbulence intensities, Reynolds’ stresses, and the wall friction in a radial wall jet formed by an impinging circular jet on a smooth flat plate. The mean velocities of the wall jet are found to be similar and can be correlated with the maximum velocity and jet thickness at each station, except for a mild Reynolds number dependence near the wall. The dimensionless radial velocity profile is in good agreement with the form suggested by Glauert [1] although the variation of the thickness of the jet does not conform to his predictions. It is shown here that this discrepancy follows from Glauert’s use of the Prandtl eddy viscosity model in describing the Reynolds’ stress distribution. Our measurements show that the shear stress does not vanish where the velocity gradient is zero, as in the case with a free jet, or as required by the eddy viscosity model. The wall friction in the wall jet is found to be larger than the corresponding friction pipe flow. This increase is probably due to the large turbulent fluctuations in the outer region of the jet, which affect the structure of the wall region.

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The tensor form of the dispersivity coefficient Dij, appearing in the equation of hydrodynamic dispersion within isotropic and axisymmetric porous mediums, is derived. It is shown that in isotropic mediums Dij/k = F1 δij + F2 υf υj l2/k2, where F1 and F2 are even functions of υl/ν and υl/k, the Reynolds and Péclet numbers. The form of Dij in the particular cases of very small and very large velocities is also discussed. Physical and dimensional considerations suggest a quadratic dependence on the velocity components for very small Reynolds and Péclet numbers and a linear dependence on the velocity components for large Reynolds numbers. Similar results are obtained for axisymmetric mediums. The relations between the dispersivity and velocity components obtained are more general than those suggested by earlier investigators.

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