Unsteady heat and/or mass transfer from a fluid sphere in creeping flow

2001 ◽  
Vol 44 (12) ◽  
pp. 2239-2246 ◽  
Author(s):  
Gh Juncu
Volume 3 ◽  
2004 ◽  
Author(s):  
Tov Elperin ◽  
Andrew Fominykh ◽  
Zakhar Orenbakh

In this study we considered mass transfer in a binary system comprising a stationary fluid dielectric sphere embedded into an immiscible dielectric liquid under the influence of an alternating electric field. Fluid sphere is assumed to be solvent-saturated so that an internal resistance to mass transfer can be neglected. Mass flux is directed from a fluid sphere to a host medium, and the applied electric field causes a creeping flow around the sphere. Droplet deformation under the influence of the electric field is neglected. The problem is solved in the approximations of a thin concentration boundary layer and finite dilution of a solute in the solvent. The thermodynamic parameters of a system are assumed constant. The nonlinear partial parabolic differential equation of convective diffusion is solved by means of a generalized similarity transformation, and the solution is obtained in a closed analytical form for all frequencies of the applied electric field. The rates of mass transfer are calculated for both directions of fluid motion — from the poles to equator and from the equator to the poles. Numerical calculations show essential (by a factor of 2–3) enhancement of the rate of mass transfer in water droplet–benzonitrile and droplet of carbontetrachloride–glycerol systems under the influence of electric field for a stagnant droplet. The asymptotics of the obtained solutions are discussed.


1986 ◽  
Vol 108 (2) ◽  
pp. 337-342 ◽  
Author(s):  
L. Sharpe ◽  
F. A. Morrison

Steady-state heat or mass transfer to a drop in an electric field at low values of the Reynolds number is investigated. The energy equation is solved using finite difference techniques; upwind differencing is used in approximating the convective terms. Far from the sphere, a “transmitting” boundary condition is introduced; the dimensionless temperature is held at zero for inward radial flow and the dimensionless temperature gradient is held at zero for outward radial flow at a fixed distance from the sphere’s surface. Numerical solutions are obtained using an iterative method. Creeping flow heat transfer results are obtained for Peclet numbers up to 103.


AIChE Journal ◽  
2010 ◽  
Vol 57 (7) ◽  
pp. 1684-1692 ◽  
Author(s):  
Abdellah Saboni ◽  
Silvia Alexandrova ◽  
Maria Karsheva ◽  
Christophe Gourdon
Keyword(s):  

Author(s):  
Adil Dani ◽  
Arnaud Cockx ◽  
Pascal Guiraud

The gas-liquid mass transfer from bubbles is estimated by Direct Numerical Simulation for fully contaminated bubbles behaving as solid spheres, partially contaminated spherical bubbles and clean spherical bubbles. Partial contamination of bubble interface is accounted by the Stagnant Cap Model to show the effect of the surfactant on hydrodynamic and mass transfer at low Reynolds number. Hydrodynamics results are validated by comparison with other works of the literature. The numerical mass transfer is then analysed in term of local and averaged Sherwood numbers. The comparison of DNS results with classical relations gives the good scaling of Sherwood with Pe1/3 and Pe1/2 respectively for solid sphere and clean bubble in creeping flow. For partially contaminated bubble and after validation of simulated drag coefficient, the effect of the contamination on mass transfer is shown for several Peclet numbers. A correlation for Sherwood number in function of contamination angle is then proposed in creeping flow.


Author(s):  
Anjun Liu ◽  
Jie Chen ◽  
Moshe Favelukis ◽  
Meng Guo ◽  
Meihong Yang ◽  
...  

1990 ◽  
Vol 112 (1) ◽  
pp. 84-91 ◽  
Author(s):  
J. N. Chung ◽  
D. L. R. Oliver

The transient heat transfer in a fluid sphere translating steadily in a dielectric medium is numerically investigated. The energy equation with velocity components of combined translation-induced and electric field-induced internal motion is integrated by the Alternating Direction Implicit (ADI) method for the entire drop interior. Creeping flow is assumed and the preponderance of the thermal resistance is assumed completely in the dispersed phase. The enhancement of heat transfer due to internal motion induced by both drop translation and the electric field is given in terms of the Nusselt number. Nusselt numbers are plotted as a function of the Fourier number, the Peclet number, and a parameter E. The parameter E represents the ratio of electric field-induced flow strength to that of translation-induced flow. In general, the heat transfer rate is approximately doubled when the flow is dominated by the electric field as compared with the case where no electric field is applied. It is suggested that for large Peclet numbers, the electric field is negligible for E less than 0.5, while the translation is unimportant for E larger than 10. For small Peclet numbers, the electric field is of minor importance for E less than 2 and the translation is insignificant for E greater than 50.


Sign in / Sign up

Export Citation Format

Share Document