Project abstract for group gulliver

Bubble-Water-Air Mass Transfer at Hydraulic Structures

Hydraulic structures such as dams and reservoirs have spillways to discharge excess water. Usually the water is discharged as a high velocity jet into a relatively stagnant pool that creates a turbulent mixing and recirculation zone. There is significant air entrainment that occurs at the water surface and jet-pool interface, resulting in large numbers of bubbles driven to depth in the pool. The additional pressure exerted on the bubble by the weight of the water results in smaller bubbles, higher oxygen and nitrogen concentrations, and ultimately higher equilibrium concentrations with the water surrounding the bubble. Thus, dissolved gases can reach a high concentration in water exposed to these bubbles, and fish equilibrate with these higher concentrations. When the fish swim towards the surface, the dissolved gases in their blood come out of solution in the lower pressures near the surface and the fish experience dissolved gas disease, similar to diver’s bends.

The principal goal of this investigation is to evaluate the performance of existing turbulent models (RANS model and LES model) in simulating bubble-water mass transfer. This is being modeled as a surface jet into a stagnant pool with bubble entrained in the jet. RANS and LES models are being used to simulate the flow. Both the distribution and mass transfer across bubbles are of primary interest in this investigation.

A bibliography of this group’s publications acknowledging MSI is attached.