Impact of Vertical, Turbulent, Planar, Negatively Buoyant Jet With Rigid Horizontal Bottom Boundary

The results of a series of laboratory modeling experiments are presented for the case of a vertical, turbulent, plane, negatively buoyant jet impinging on a horizontal solid surface placed a distance H below the jet source. The results show that the impingement results in the generation of a complex two-dimensional disturbance field at the site of the impact and the generation of a buoyancy-driven boundary current carrying away fluid from the impingement zone. The disturbance field is seen to extend vertically along the time-averaged axis of the incident buoyant jet, thereby distorting the vertical velocity and concentration fields over a vertical distance that depends upon the value of the parameter Fd0?4/3, where Fd0 is the source Froude number of the buoyant jet. Transverse velocity and concentration profiles taken at different axial distances from the source reveal systematic departures from the far-field Gaussian similarity profiles as the solid boundary is approached. Such departures are utilized to quantify and parameterize the vertical distance z??? from the boundary at z = 0 beyond which the impingement of the buoyant jet does not affect significantly the incident flow. Measurements indicate that z???/b ～ 0.4Fd04/3. For distances z