Momentum and Mass Transfer in Coaxial Gas Jets

1950 ◽  
Vol 17 (4) ◽  
pp. 399-408 ◽  
Author(s):  
Walton Forstall ◽  
Ascher H. Shapiro
Keyword(s):  
Mass Transfer ◽  
Momentum Transfer ◽  
Integral Method ◽  
Constant Pressure ◽  
Velocity Ratio ◽  
Moving Medium ◽  
Density Data ◽  
Gas Jets ◽  
Schmidt Numbers ◽  
Independent Variable

Abstract The mixing at constant pressure of a circular jet with an annular coaxial stream has been studied for conditions of nearly common density and temperature, but differing initial velocities. By using 10 per cent by volume of helium as a tracer in the inner stream, the mixing region was mapped with respect to both material and momentum transfer. It is concluded that material diffuses more rapidly than momentum; that the principal independent variable determining the shape of the mixing region is the velocity ratio of the streams; and that the integral method of Squire and Trouncer, using experimentally determined constants, is adequate for predicting approximate values of concentration and velocity in the mixing region of a jet flowing into a moving medium of the same density. Data for widely different experiments of various investigators show that the turbulent Prandtl and the Schmidt numbers are both within ±10 per cent of 0.70, independent of the nature of the experiment and the magnitudes of the laminar Prandtl and Schmidt numbers.

Mass transfer into the liquid in turbulent flow at high Schmidt numbers. Dissolution of benzoic acid into aqueous solutions of glycerol from internal surface of the pipe

1981 ◽  
Vol 46 (7) ◽  
pp. 1566-1576
Author(s):  
František Vašák ◽  
Václav Kolář ◽  
Zdeněk Brož
Keyword(s):  
Mass Transfer ◽  
Benzoic Acid ◽  
Aqueous Solutions ◽  
Cross Section ◽  
Circular Cross Section ◽  
Internal Surface ◽  
Theoretical Relation ◽  
Acid Dissolution ◽  
Schmidt Numbers ◽  
Unified Description

Theoretical relation derived in the last study for calculation of the mass transfer coefficient in the region of not fully developed concentration profile at high Schmidt numbers has been verified experimentally. This experimental study has been devoted to measurements of the rate of benzoic acid dissolution into aqueous solutions of glycerol from the internal surface of the pipe of circular cross section in the range 933 ⪬ Sc ⪬ 225 000 and 5 000 ⪬ Re ⪬ 50 000. It has been possible to explain on basis of the theoretical model, the differences between the data of various authors and to obtain a unified description of the phenomena.

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

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.

scholarly journals Direct numerical simulation of turbulent scalar transport across a flat surface

2014 ◽  
Vol 744 ◽  
pp. 217-249 ◽  
Author(s):  
H. Herlina ◽  
J. G. Wissink
Keyword(s):  
Mass Transfer ◽  
Isotropic Turbulence ◽  
Reynolds Numbers ◽  
Gas Transfer ◽  
Computational Domain ◽  
Atmospheric Gases ◽  
Transfer Velocity ◽  
Physical Mechanisms ◽  
Schmidt Numbers ◽  
Large Eddies

AbstractTo elucidate the physical mechanisms that play a role in the interfacial transfer of atmospheric gases into water, a series of direct numerical simulations of mass transfer across the air–water interface driven by isotropic turbulence diffusing from below has been carried out for various turbulent Reynolds numbers ($R_T=84,195,507$). To allow a direct (unbiased) comparison of the instantaneous effects of scalar diffusivity, in each of the DNS up to six scalar advection–diffusion equations with different Schmidt numbers were solved simultaneously. As far as the authors are aware this is the first simulation that is capable to accurately resolve the realistic Schmidt number, $\mathit{Sc}=500$, that is typical for the transport of atmospheric gases such as oxygen in water. For the range of turbulent Reynolds numbers and Schmidt numbers considered, the normalized transfer velocity $K_L$ was found to scale with $R_T^{-{1/2}}$ and $\mathit{Sc}^{-{1/2}}$, which indicates that the largest eddies present in the isotropic turbulent flow introduced at the bottom of the computational domain tend to determine the mass transfer. The $K_L$ results were also found to be in good agreement with the surface divergence model of McCready, Vassiliadou & Hanratty (AIChE J., vol. 32, 1986, pp. 1108–1115) when using a constant of proportionality of 0.525. Although close to the surface large eddies are responsible for the bulk of the gas transfer, it was also observed that for higher $R_T$ the influence of smaller eddies becomes more important.

Exact solutions for a class of nonlinear free surface flows

1991 ◽  
Vol 434 (1892) ◽  
pp. 677-682 ◽  
Keyword(s):  
Free Surface ◽  
Free Boundary ◽  
Infinite System ◽  
Free Stream ◽  
Constant Pressure ◽  
Velocity Ratio ◽  
Mapping Function ◽  
Free Surface Flows ◽  
Surface Flows ◽  
Nonlinear Free Surface

We consider a class of inviscid free surface flows where the free surface is of finite length and in which the pressure on the free boundary p b is different from the free stream pressure p ∞ . The aim of the paper is to determine the shape of the free surface as a function of the velocity ratio parameter λ . The free boundary problem is tackled by seeking a mapping z ═ f (ζ) such that the flow past a circle in the ζ-plane maps to a flow with constant pressure p b on the free surface in the z -plane. The formulation leads to an infinite system of coupled nonlinear equations for the coefficients in the mapping function. Remarkably, the system can be solved exactly to yield two families of free surface flows of the form z ═ ζ + λ 2 /ζ + a ( λ ) ln (ζ + b ( λ )/ζ ─ b ( λ )). The nature of the solutions, their limitations and possible extensions to them are discussed.

Heat and Mass Transfer Porous Medium Saturated with Compressible Fluid with Boundary Domain Integral Method

2008 ◽  
Vol 273-276 ◽  
pp. 808-813 ◽  
Author(s):  
Janja Kramer ◽  
Renata Jecl ◽  
Leo Škerget
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Heat And Mass Transfer ◽  
Compressible Fluid ◽  
Integral Method ◽  
Stokes Equations ◽  
Numerical Approach ◽  
Momentum Equation ◽  
Navier Stokes ◽  
Domain Integral

A numerical approach to solve a problem of combined heat and mass transfer in porous medium saturated with compressible fluid is presented. Transport phenomena in porous media is described using the modified Navier-Stokes equations, where for the governing momentum equation the Brinkman extended Darcy formulation is used. Governing equations are solved with the Boundary Domain Integral Method, which is an extension of classical Boundary Element Method.

An Analytical Model for Boundary Layer Control Via Steady Blowing and Its Application to NACA-65-410 Cascade

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Mehmet N. Sarimurat ◽  
Thong Q. Dang
Keyword(s):  
Boundary Layer ◽  
Analytical Model ◽  
Integral Method ◽  
Velocity Ratio ◽  
Control Technique ◽  
Momentum Thickness ◽  
Compressor Cascade ◽  
Low Speed ◽  
Momentum Coefficient ◽  
Velocity Magnitude

In this paper, boundary-layer flow-control technique via steady blowing for low-speed compressor cascade applications is investigated using an analytical model based on the integral method and computational fluid dynamics (CFD). The integral method is developed and used to investigate the effect of the momentum, the velocity magnitude, and the angle of the blowing flow on the behavior of the boundary layer. It is found that the change in the boundary layer momentum thickness across the blowing location is a linear function of the blown-flow momentum coefficient and a decaying function of the blown-flow velocity ratio. For the case when the size of the blowing slot and the velocity magnitude of the blown-flow are kept constant and the blowing mass flow rate is increased by increasing the blowing angle, there is an “optimum” blowing angle that maximizes the benefit of the boundary layer blowing. This angle increases with increasing velocity ratio and reaches an asymptotic value of 45 deg. According to the model, the change in the momentum thickness across the blowing location is conveyed exponentially downstream; thus, a small change in the momentum thickness due to flow blowing can have significant effect downstream. The developed model is applied to the NACA-65-410 low speed cascade using CFD, and good agreement between theory and CFD is obtained.

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