Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/7405
Title: MAC3D: Numerical model for reservoir hydrodynamics with application to bubble diffusers
Authors: Bernard, Robert S.
Keywords: Bubble plume
Computational fluid dynamics
Gas transfer
Incompressible flow
Turbulence model
Publisher: Coastal and Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; CHL-98-23.
Description: Technical report
The MAC3D numerical model, a three-dimensional flow solver initially developed for reservoir hydrodynamics, has been extended to account for the flow and gas transfer induced by bubble plumes. The latter are represented as buoyant columns in which dissolved gas is transferred to or from surrounding water. The local transfer rate is proportional to the dissolved gas concentration, and the resulting flow and gas transport are computed by solving discrete equations for the conservation of mass and momentum. The upward force imposed by a bubble column is directly proportional to the airflow rate through the associated bubble diffuser, and inversely proportional to the local depth and the bubble rise velocity. Gas-transfer coefficients are empirical quantities that have to be inferred from laboratory experiments, but eddy viscosity and diffusivity are obtained directly from a k- € turbulence model. In the numerical solution of the governing equations, the (previously used) explicit MacCormack scheme has been replaced by an implicit upwind scheme that improves stability and reduces execution time by a factor of five to ten. In this report, the model is validated for unstratified or weakly stratified water bodies by comparing predicted velocities and gas-transfer rates with data from laboratory experiments and field tests using coarse- and fine-bubble diffusers.
Rights: Approved for public release; distribution is unlimited.
URI: http://hdl.handle.net/11681/7405
Appears in Collections:Technical Report

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