Interferometric Observation of Turbulent Mass Transfer in Channel Flow

Characteristics of turbulent mass transfer around a rotating circular cylinder have been investigated by Direct Numerical Simulation. The concentration field was computed for three different cases of Schmidt number, Sc = 1, 10 and 100 at ReR* = 336. Our results confirm that the thickness of the Nernst diffusion layer decreases as Sc increases. Wall-limiting behavior within the diffusion layer was examined and compared with that of channel flow. Concentration fluctuation time scale was found to scale with r+2, while the time scale ratio nearly equals the Schmidt number throughout the diffusion layer. Scalar modeling closure constants based on gradient diffusion models were found to vary considerably within the diffusion layer. Results of an octant analysis show the significant role played by the ejection and sweep events just as is found for flat plate, channel, and pipe flow boundary layers. Turbulence budgets revealed a strong Sc dependence of turbulent scalar transport.

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Turbulent Mass Transfer Simulations of Binary Electrolyte in Parallel-Plate Electrode Channel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.550-553.2014 ◽

2012 ◽

Vol 550-553 ◽

pp. 2014-2018

Author(s):

Xiao Lan Zhou ◽

Cai Xi Liu ◽

Yu Hong Dong

Keyword(s):

Mass Transfer ◽

Turbulent Flows ◽

Primary Objective ◽

Wall Turbulence ◽

Limiting Current ◽

Solid Boundary ◽

Wall Region ◽

Schmidt Numbers ◽

Near Wall ◽

Turbulent Mass Transfer

Electrochemical mass transfer in turbulent flows and binary electrolytes is investigated. The primary objective is to provide information about mass transfer in the near-wall region between a solid boundary and a turbulent fluid flow at different Schmidt numbers. Based on the computational fluid dynamics and electrochemistry theories, a model for turbulent electrodes channel flow is established. The turbulent mass transfer in electrolytic processes has been predicted by the direct numerical simulation method under limiting current and galvanostatic conditions, we investigate mean concentration and the structure of the concentration fluctuating filed for different Schmidt numbers from 0.1 to 100 .The effect of different concentration boundary conditions at the electrodes on the near-wall turbulence statistics is also discussed.

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Heat and mass transfer in turbulent multiphase channel flow

10.3990/1.9789036538817 ◽

2015 ◽

Author(s):

Anastasia Bukhvostova

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Channel Flow

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Water droplet condensation and evaporation in turbulent channel flow

Journal of Fluid Mechanics ◽

10.1017/jfm.2014.239 ◽

2014 ◽

Vol 749 ◽

pp. 666-700 ◽

Cited By ~ 20

Author(s):

E. Russo ◽

J. G. M. Kuerten ◽

C. W. M. van der Geld ◽

B. J. Geurts

Keyword(s):

Mass Transfer ◽

Nusselt Number ◽

Size Distribution ◽

Water Vapour ◽

Channel Flow ◽

Droplet Size ◽

Droplet Size Distribution ◽

Turbulent Channel Flow ◽

Phase Changes ◽

Cold Wall

AbstractWe propose a point-particle model for two-way coupling of water droplets dispersed in the turbulent flow of a carrier gas consisting of air and water vapour. We adopt an Euler–Lagrangian formulation based on conservation laws for the mass, momentum and energy of the continuous phase and on empirical correlations describing momentum, heat and mass transfer between the droplet phase and the carrier gas phase. An incompressible flow formulation is applied for direct numerical simulation of differentially heated turbulent channel flow. The two-way coupling is investigated in terms of its effects on mass and heat transfer characteristics and the resulting droplet size distribution. Compared to simulations without droplets or those with solid particles with the same size and specific heat as the water droplets, a significant increase in Nusselt number is found, arising from the additional phase changes. The Nusselt number increases with increasing ambient temperature and is almost independent of the heat flux applied to the walls of the channel. The time-averaged droplet size distribution displays a characteristic dependence on position expressing the combined effect of turbophoresis and phase changes in turbulent wall-bounded flow. In the statistically steady state that is reached after a long time, the resulting flow exhibits a mean motion of water vapour from the warm wall to the cold wall, where it condenses on average, followed by a net mean mass transfer of droplets from the cold wall to the warm wall.

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