Study Compares 2D and 3D Model Simulations of Oil Plume Behavior
June 4, 2019
Scientists assessed an economical 2D model simulation of deep-ocean oil plume dynamics against 3D model results using conditions similar to Deepwater Horizon to better understand point-source buoyant convection, which affects the oil’s spreading rate and environmental impact. The 2D model worked best for thermal plumes without bubbles. Although the 2D model successfully captured the transition from a constant volume flux jet to a thermal plume near the wellhead, it did not capture turbulence at the wellhead. Comparisons of both model simulations uncovered an unexpected influence of the Earth’s rotation on near-field swirl speeds, an effect not typically included in classical oil/gas plume models. Given this new insight, the authors suggested exploring other physics normally recognized as leading-order important, such as cross flow and time variable background fields, in the presence of rotation.
The researchers published their findings in Ocean Modelling: Rotating 2d point source plume models with application to Deepwater Horizon.
Historically, environmental modeling of a multiphase oil plume has used a Lagrangian framework, where particles representing oil droplets and gas bubbles with evolving physio-chemical properties are advected by an imposed background flow field. Earlier studies compared Lagrangian models applied to the Deepwater Horizon event (Marine Pollution Bulletin Socolofsky et al., 2015) and applied a turbulence-resolving model to plumes in a thermally-stratified environment (Journal of Geophysical Research: Oceans Fabregat et al., 2016, 2017) in rotating and nonrotating settings. These studies showed that rotating multiphase plumes differed dramatically from non-rotating cases and that buoyant plumes do not rise in a straight path from the source even when there is relatively slow planetary rotation. Rather, buoyant plumes twist sideways and precess about the vertical axis, significantly changing the turbulent mixing properties and the vertical distribution of plume effluent.