Large-eddy simulation of double-plume formation induced by CO2 dissolution in the ocean

Abstract

Using two-fluid LES technology, a numerical model is developed to simulate double-plume formation under conditions relevant to CO 2 ocean sequestration applications. A small-scale ocean turbulent flow is created and maintained by a forced-dissipative mechanism and LES. Data on ocean currents, temperature and salinity were employed by the model as inlet boundary and initial conditions, respectively. A set of empirical formulae, calibrated with laboratory experimental data, was developed to describe momentum, mass and heat transfer phenomena. Using this model, the influence of the initial diameter of CO 2 droplets released in the deep ocean and thermal effects on the structure of two plumes were investigated. The height of the CO 2 droplet plume and the local minimum pH within the CO 2 -enriched seawater plume were found to be very sensitive to the initial diameter of injected CO 2 droplets. Plume height and pH are two key parameters to assess CO 2 sequestration efficiency and related biological impacts. Thermal effects associated with CO 2 dissolution appeared to have limited influence on CO 2 -enriched seawater plume structure and pH, but can significantly affect the LCO 2 plume and the temperature field near the CO 2 injection nozzle.

Three‐dimensional acoustic monitoring and modeling of a deep‐sea CO2 droplet cloud

“…Comparison of the ROV borne 675 kHz sonar signal of horizontal slices through the rising cloud at 5, 15, and 25 minutes after release with a (top) numerical model [ Chen et al , 2003] and (bottom) with grid scales in meters.…”

“…The cloud was detectable from the surface ship for over 30 minutes, and through 150 m of ascent. (b) Numerical model of the vertical extent of the cloud [ Chen et al , 2003] at 5, 15, and 25 minutes after release.…”

“…[13] We performed two numerical simulations of the 5-L release, one by a single CO 2 droplet simulation incorporating dissolution rates and buoyancy forces calibrated by laboratory and field studies to determine the initial sizes of droplets, and another by a turbulent two-phase cloud model [Chen et al, 2003] to predict droplet cloud dynamics.…”

“…The difficulty of observing a freely released rising CO 2 cloud is such that only very small scale observations of individual rising droplets [ Brewer et al , 2002] have been reported so far. These few observations have been used as input for sophisticated models [ Alendal and Drange , 2001; Chen et al , 2003; Sato , 2004; Gangstø et al , 2005] of larger scale CO 2 clouds, but no observational constraints have yet been available to guide and test model development.…”

Goldschmidt Abstracts 2007- C

“…The model (Chen et al, 2003) used in this study is a full two-phase small-scale turbulent ocean model, of which the submodels had been calibrated by both Lab. experiments and field observations.…”