scholarly journals A Radiometric Method to Measure the Concentration Boundary Layer Thickness at an Air–Water Interface*

1997 ◽  
Vol 14 (6) ◽  
pp. 1494-1501 ◽  
Author(s):  
Walt McKeown ◽  
William Asher
Keyword(s):  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Radiometric Method ◽  
Concentration Boundary Layer ◽  
Water Interface ◽  
Concentration Boundary ◽  
Air Water Interface

Mass Transfer around a Sphere Buried in a Packed Bed

2014 ◽  
Vol 353 ◽  
pp. 306-310
Author(s):  
João M.P.Q. Delgado ◽  
M. Vázquez da Silva
Keyword(s):  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Numerical Solutions ◽  
Concentration Field ◽  
Particle Diameter ◽  
Packed Bed ◽  
Concentration Boundary Layer ◽  
Concentration Boundary ◽  
Mass Transfers

The transport phenomenon of mass transfers between a moving fluid and a reacting sphere buried in a packed bed, with “uniform velocity”, was analysed numerically, for solute transport by both advection and diffusion to obtain the concentration field and, from it, the dimensionless concentration boundary layer thickness, , for , and . The bed of inert particles is taken to have uniform voidage. For this purpose, numerical solutions of the partial differential equations describing mass concentration of the solute were undertaken to obtain the concentration boundary layer thickness as a function of the relevant parameters. Finally, mathematical expressions that relate the dependence with the Peclet number and inert particle diameter are proposed to describe the approximate size of the concentration boundary layer thickness.

Flow Past a Sphere Buried in a Porous Media: Concentration Boundary Layer Thickness

2015 ◽  
Vol 3 ◽  
pp. 41-59 ◽  
Author(s):  
João M.P.Q. Delgado ◽  
M. Vázquez da Silva
Keyword(s):  
Boundary Layer ◽  
Numerical Solution ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Surface Concentration ◽  
Packed Bed ◽  
Solid Sphere ◽  
Concentration Boundary Layer ◽  
Concentration Boundary ◽  
Media Concentration

In this work, consideration is given to the problem of dissolution of a buried solid sphere in the liquid flowing uniformly through the packed bed around it. The differential equations describing fluid flow and mass transfer by advection and diffusion in the interstices of the bed are presented and the method for obtaining their numerical solution is indicated.From the surface concentration fields, given by the numerical solution, the concentration boundary layer thickness as a function of the relevant parameters were undertaken. Mathematical expressions that relate the dependence with the Peclet number and d/d1 ratio of an immersed active sphere are proposed to describe the approximate size of the concentration boundary layer thickness.

Self-consistent unstirred layers in osmotically driven flows

2010 ◽  
Vol 662 ◽  
pp. 197-208 ◽  
Author(s):  
K. H. JENSEN ◽  
T. BOHR ◽  
H. BRUUS
Keyword(s):  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layers ◽  
Boundary Layer Thickness ◽  
Concentration Boundary ◽  
Concentration Boundary Layers ◽  
Unstirred Layers ◽  
Mathematical Relation ◽  
Wide Range ◽  
Self Consistent

It has long been recognized that the osmotic transport characteristics of membranes may be strongly influenced by the presence of unstirred concentration boundary layers adjacent to the membrane. Previous experimental as well as theoretical works have mainly focused on the case where the solutions on both sides of the membrane remain well mixed due to an external stirring mechanism. We investigate the effects of concentration boundary layers on the efficiency of osmotic pumping processes in the absence of external stirring, i.e. when all advection is provided by the osmosis itself. This case is relevant in the study of intracellular flows, e.g. in plants. For such systems, we show that no well-defined boundary-layer thickness exists and that the reduction in concentration can be estimated by a surprisingly simple mathematical relation across a wide range of geometries and Péclet numbers.

Similarity problems of the theory of unsteady concentration boundary layer

1983 ◽  
Vol 48 (10) ◽  
pp. 2751-2766
Author(s):  
Ondřej Wein ◽  
N. D. Kovalevskaya
Keyword(s):  
Boundary Layer ◽  
Approximate Method ◽  
Steady Flow ◽  
Broad Class ◽  
Concentration Boundary Layer ◽  
Concentration Change ◽  
Concentration Boundary ◽  
Flow Problems

Using a new approximate method, transient course of the local and mean diffusion fluxes following a step concentration change on the wall has been obtained for a broad class of steady flow problems.

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