Determination of the discharge coefficient through vent driven by a non-Boussinesq plume in an emptying filling box

Abstract

The effect of high buoyancy forces due to density contrast between the fluids on either side of the vent on the discharge coefficient Cd is taken into account in the laboratory. Salt water experiments are conducted at small scale in a large fresh water tank with saline to generate buoyancy force. In non-Boussinesq cases, a larger discharge parameter Γd at the vent may make plume-like flow contract further with a smaller value of the discharge coefficient. A nearly twofold time in the non-dimensional form for draining light fluid fully out of the space is observed comparing with time predicted with a constant value of Cd = 0.6 for simple draining flows. A displacement flow theoretical model with virtual source correction at the initial position of an internal source is developed to reveal a time-dependent movement of the layer interface, and the oscillatory amplitude of the interface overshooting during the transient period is found to depend on the two dimensionless geometrical parameters Λ and Θ.