Convective diffusion across a porous diaphragm

The problem of convective diffusion toward the sphere in laminar flow around the sphere is solved by combination of the analytical and net methods for the region of Peclet number λ ≥ 1. The problem was also studied for very small values λ. Stability of the solution has been proved in relation to changes of the velocity profile.

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Influence of free convection on the diffusion current to a sphere in a laminar forced flow regime

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19852697 ◽

1985 ◽

Vol 50 (12) ◽

pp. 2697-2714

Author(s):

Arnošt Kimla ◽

Jiří Míčka

Keyword(s):

Asymptotic Expansion ◽

Free Convection ◽

Boundary Value Problem ◽

Concentration Gradient ◽

Empirical Formula ◽

Convective Diffusion ◽

Forced Flow ◽

Diffusion Current ◽

Wide Range ◽

Free And Forced Convection

The formulation and solution of a boundary value problem is presented, describing the influence of the free convective diffusion on the forced one to a sphere for a wide range of Rayleigh, Ra, and Peclet, Pe, numbers. It is assumed that both the free and forced convection are oriented in the same sense. Numerical results obtained by the method of finite differences were approximated by an empirical formula based on an analytically derived asymptotic expansion for Pe → ∞. The concentration gradient at the surface and the total diffusion current calculated from the empirical formula agree with those obtained from the numerical solution within the limits of the estimated errors.

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Convective diffusion to a slowly rotating spherical electrode; Basic model for Re → O, Pe → ∞

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19831571 ◽

1983 ◽

Vol 48 (6) ◽

pp. 1571-1578 ◽

Cited By ~ 1

Author(s):

Ondřej Wein

Keyword(s):

Boundary Layer ◽

Flow Regime ◽

Peclet Number ◽

Convective Diffusion ◽

Creeping Flow ◽

Péclet Number ◽

Spherical Electrode ◽

Basic Model ◽

Boundary Layer Solution ◽

Layer Solution

Theory has been formulated of a convective rotating spherical electrode in the creeping flow regime (Re → 0). The currently available boundary layer solution for Pe → ∞ has been confronted with an improved similarity description applicable in the whole range of the Peclet number.

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On the convective diffusion under partial slip at wall

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19890967 ◽

1989 ◽

Vol 54 (4) ◽

pp. 967-980 ◽

Cited By ~ 3

Author(s):

Ondřej Wein ◽

Petr Kučera

Keyword(s):

Mass Transfer ◽

Numerical Solution ◽

Analytic Solution ◽

Convective Diffusion ◽

Linear Velocity ◽

Partial Slip ◽

Accurate Calculation ◽

Transfer Coefficients ◽

Empirical Formulas ◽

Mass Transfer Coefficients

Extended Leveque problem is studied for linear velocity profiles, vx(z) = u + qz. The existing analytic solution is reconsidered and shown to be inapplicable for the accurate calculation of mean mass-transfer coefficients. A numerical solution is reported and its accuracy is checked in detail. Simple but fairly accurate empirical formulas are suggested for the calculating of local and mean mass-transfer coefficients.

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Transient convective diffusion to a uniformly accessible surface under aparent slip conditions

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19910334 ◽

1991 ◽

Vol 56 (2) ◽

pp. 334-343

Author(s):

Ondřej Wein

Keyword(s):

Power Law ◽

Analytical Solutions ◽

Convective Diffusion ◽

Active Surface ◽

Velocity Profiles ◽

One Dimensional ◽

Slip Conditions ◽

Accessible Surface ◽

Diffusion Problems

Analytical solutions are given to a class of unsteady one-dimensional convective-diffusion problems assuming power-law velocity profiles close to the transport-active surface.

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