Experimental investigation of single value variables of three-dimensional density current

The height of a dense layer underflow is defined as the interface between a dyed saline solution fluid and colorless ambient fluid. In this paper, the density current height or vision height of three-dimensional saline water under pure water is measured empirically, and the relation of this parameter with the location of maximum velocity is investigated. Because of the absence of a clear interface between the dense underflow and pure water, researchers were unable to define a unique parameter for the evaluation of density current height. The parameters used by some researchers include the height corresponding to the location of maximum, half-maximum, and quarter-maximum velocity in the velocity profiles. In this work, the velocity components were measured by an acoustic Doppler velocimeter (ADV), and corresponding parameters were computed based on these velocities. In this laboratory, channel walls were made of glass, so in all experiments the vision height of the dense layer could be measured. Therefore, a relation between the velocity profiles and the dense layer height was established. Results show that dense layer height has a close correlation with height corresponding to the location of the quarter-maximum velocity. Finally, the effects of concentration, bed slope, and discharge on the dense layer height were studied. Experimental data also show that an increase in the inlet flow rate leads to an increase in the dense layer height, and this parameter decreases with an increase in the bed slope or concentration.