Mass Transfer between Solid Wall and Fluid Streams. Interferometric Measurements of Concentration Profiles in Turbulent and Streamline Flow.

1953 ◽  
Vol 45 (3) ◽  
pp. 640-646 ◽  
Author(s):  
C. Lin ◽  
R. Moulton ◽  
G. Putnam
Keyword(s):  
Mass Transfer ◽  
Solid Wall ◽  
Concentration Profiles ◽  
Streamline Flow

Modeling mass transfer and substrate utilization in the boundary layer of biofilm systems

1998 ◽  
Vol 37 (4-5) ◽  
pp. 139-147 ◽  
Author(s):  
Harald Horn ◽  
Dietmar C. Hempel
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Film Theory ◽  
Substrate Utilization ◽  
The Other ◽  
Concentration Profiles ◽  
Hydrodynamic Conditions ◽  
Time Axis ◽  
Transfer Coefficients

The use of microelectrodes in biofilm research allows a better understanding of intrinsic biofilm processes. Little is known about mass transfer and substrate utilization in the boundary layer of biofilm systems. One possible description of mass transfer can be obtained by mass transfer coefficients, both on the basis of the stagnant film theory or with the Sherwood number. This approach is rather formal and not quite correct when the heterogeneity of the biofilm surface structure is taken into account. It could be shown that substrate loading is a major factor in the description of the development of the density. On the other hand, the time axis is an important factor which has to be considered when concentration profiles in biofilm systems are discussed. Finally, hydrodynamic conditions become important for the development of the biofilm surface when the Reynolds number increases above the range of 3000-4000.

Transient Free Convection Mass Transfer of Second-grade Fluid Flow with Wall Transpiration

CFD Letters ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 35-52
Author(s):  
Mohamad Alif Ismail ◽  
Mohamad Hidayad Ahmad Kamal ◽  
Lim Yeou Jiann ◽  
Anati Ali ◽  
Sharidan Shafie
Keyword(s):  
Mass Transfer ◽  
Schmidt Number ◽  
Second Grade ◽  
Concentration Profiles ◽  
Governing Equations ◽  
Second Grade Fluid ◽  
Wall Suction ◽  
Viscoelastic Parameter ◽  
Grade Fluid ◽  
Wall Injection

The study of mass transfer in the non-Newtonian fluid is essential in understanding the engine lubrication, the cooling system of electronic devices, and the manufacturing process of the chemical industry. Optimal performance of the practical applications requires the appropriate conditions. The unsteady transient free convective flow of second-grade fluid with mass transfer and wall transpiration is concerned in the present communication. The behavior of the second-grade fluid under the influence of injection or suction is discussed. Suitable non-dimensional variables are utilized to transform the governing equations into non-dimensional governing equations. A Maple solver “pdsolve” that is using the centered implicit scheme of a finite difference method is utilized to solve the dimensionless governing equations numerically. The effects of wall injection or suction parameter, second-grade fluid viscoelastic parameter, Schmidt number, and modified Grashof number on the velocity and concentration profiles are graphically displayed and analyzed. The results show that with increasing wall suction, viscoelastic parameter, and Schmidt number, the velocity and concentration profiles decrease. Whereas, the velocity profiles show an opposite tendency in situations of wall injection. The wall suction has increased the skin friction and also the rate of mass diffusion in the second-grade fluid.

Enhancement of Turbulent Shear Stress and Mass Transfer in Wall Turbulence Accompanied With Wall Blowing

2016 ◽  
Author(s):  
Yushi Okamura ◽  
Hideaki Sugioka ◽  
Yasuo Kawaguchi
Keyword(s):  
Mass Transfer ◽  
Shear Stress ◽  
Spatial Distribution ◽  
Solid Wall ◽  
Structural Parameters ◽  
Wall Turbulence ◽  
Experimental Result ◽  
Turbulent Shear ◽  
Eddy Structure ◽  
Turbulent Schmidt Number

Spatial distribution of velocity and mass concentration fluctuation in turbulent channel flow with wall blowing were simultaneously measured by PIV/PLIF. The recorded pictures were analyzed to clarify the turbulent momentum and mass transfer from statistical view point and from spatial evolution of coherent eddy structure. Experimental result revealed that the Reynold shear stress and turbulent intensity are enhanced as the blowing rate increasing. On the other hand, structural parameters based on local turbulence such as turbulent Schmidt number and a degree of turbulent anisotropy is not affected by wall blowing. In comparison without wall blowing, we found that the turbulent eddy structure locates apart from the wall. Besides, energy spectrum and swirling strength is also enhanced by wall blowing. It is associated with increase of resistance by wall blowing. Generally in wall turbulence, fluctuation motions are restricted by the presence of solid wall. But for the blowing from the wall relaxes this restriction and Reynolds shear stress is enhanced, which leads to enhancement of turbulent mass flux. Moreover, from results of spatial distribution of instantaneous fields, wall-blowing helps development of hairpin vortexes. It is concluded that development of hairpins leads to enhancement of turbulent mass transfer.

Non-axisymmetric turbulent mass transfer in a circular tube

1969 ◽  
Vol 38 (3) ◽  
pp. 457-472 ◽  
Author(s):  
Alan Quarmby ◽  
R. K. Anand
Keyword(s):  
Mass Transfer ◽  
Circular Tube ◽  
Eddy Diffusivity ◽  
Concentration Profiles ◽  
Tracer Gas ◽  
Direct Evaluation ◽  
Measured Concentration ◽  
Eddy Diffusivities ◽  
Fluid Properties ◽  
Fully Developed Turbulent Flow

Theory and experiment are presented for mass transfer into a fully developed turbulent flow in a plain circular tube in two non-axisymmetric cases. The cases studied are a diametral line source and a discontinuous ring source, in which there is a uniform mass flux over rectangular areas of the tube wall. A comparison is made between the concentration profiles predicted by the solutions of the diffusion equation and experiments using nitrous oxide, Schmidt number S = 0·77, as a tracer gas in air. The range of experiments covers Reynolds numbers R from 20,000 to 120,000.In the analysis, the assumption is made that the tangential and radial eddy diffusivities of mass are equal at a point. The radial diffusivity of mass, which is a function of radial position, is related to the radial eddy diffusivity of momentum by a ratio, which takes account of fluid properties and the value of the radial eddy diffusivity of momentum. The satisfactory agreement between analysis and experiment establishes the correctness of this assumption. Further confirmation was obtained by direct evaluation of the tangential eddy diffusivity of mass from the measured concentration profiles.

scholarly journals Heat and Mass Transfer during Hydrogen Generation in an Array of Fuel Bars of a BWR Using a Periodic Unit Cell

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
H. Romero-Paredes ◽  
F. J. Valdés-Parada ◽  
G. Espinosa-Paredes
Keyword(s):  
Mass Transfer ◽  
Numerical Analysis ◽  
Fuel Element ◽  
Numerical Simulations ◽  
Heat And Mass Transfer ◽  
Nuclear Reactor ◽  
Hydrogen Generation ◽  
Unit Cell ◽  
Concentration Profiles ◽  
Periodic Unit Cell

This paper presents, the numerical analysis of heat and mass transfer during hydrogen generation in an array of fuel cylinder bars, each coated with a cladding and a steam current flowing outside the cylinders. The analysis considers the fuel element without mitigation effects. The system consists of a representative periodic unit cell where the initial and boundary-value problems for heat and mass transfer were solved. In this unit cell, we considered that a fuel element is coated by a cladding with steam surrounding it as a coolant. The numerical simulations allow describing the evolution of the temperature and concentration profiles inside the nuclear reactor and could be used as a basis for hybrid upscaling simulations.

Mass Transfer Cooling of Laminar Flow Between Parallel Porous Plates

1974 ◽  
Vol 96 (3) ◽  
pp. 343-347 ◽  
Author(s):  
G. Walker ◽  
R. M. Terrill
Keyword(s):  
Mass Transfer ◽  
Nusselt Number ◽  
Mass Concentration ◽  
Energy Equation ◽  
Analytic Solutions ◽  
Thermal Capacity ◽  
Injection Velocity ◽  
Concentration Profiles ◽  
Nonisothermal Flow ◽  
Two Dimensional

The limiting temperature and mass concentration profiles and the limiting wall Nusselt number are obtained for the laminar nonisothermal flow in a two-dimensional porous channel. Results are reported for a uniform rate of injection at the wall of a foreign component of higher thermal capacity than the fluid in the channel. An exact solution of the diffusion equation is found while numerical and analytic solutions of the energy equation are discussed for small injection rates. It is shown that the enthalpy transport resulting from the diffusion process has an effect equivalent to increasing the Prandtl number. It is also found that for a given injection velocity at the wall, the limiting Nusselt number is significantly reduced by the injection of a foreign component of high thermal capacity.

Passive Vortex Micromixers Utilizing Hybrid Laminations

2008 ◽  
Author(s):  
Jyh-Jian Chen ◽  
Yu-Cheng Luo ◽  
Shin-Hau Su ◽  
Nai-Yu Jheng
Keyword(s):  
Mass Transfer ◽  
Theoretical Investigation ◽  
Vortex Flow ◽  
Three Dimensional ◽  
Taylor Number ◽  
Concentration Profiles ◽  
Mixing Index ◽  
Mixing Performance ◽  
Damping Effect ◽  
Square Prism

This theoretical investigation analyzed the three-dimensional momentum and mass transfer characteristics arising from the multiple inlets and single outlet in micro chamber which consists of a right square prism, an octagonal prism or a cylinder. The effects of various geometric parameters, inlet velocities, and the types of lamination on the mixing characteristics were investigated, and the results were presented in terms of flow fields, concentration profiles, and mixing index. Numerical results indicated that vortex flow and numbers of inlets dominate the mixing index. At larger Taylor number, more inertia caused the powerful vortex flow in the chamber, and the damping effect on diffusion was diminished, which then increased the mixing performance. Furthermore, passive micromixers utilizing hybrid laminations showed better mixing results than those with parallel laminations.

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