TY - JOUR
TI - Mass transfer and concentration contours around surfaces buried in granular beds and exposed to fluid flow
T2 - Defect and Diffusion Forum
VL - 258-260
SP - 592-599
PY - 2006
DO - 10.4028/www.scientific.net/DDF.258-260.592
AU - Quesado Delgado, J.
AU - Alves, M.
AU - Carvalho, J.
AB - This work describes the process of mass transfer which takes place when a fluid flows
past a soluble surface buried in a packed bed of small inert spherical particles of uniform voidage.
The fluid is assumed to have uniform velocity far from the buried surface and different surface
geometries are considered; namely, cylinder in cross flow and in flow aligned with the axis, flat
surface aligned with the flow and sphere.
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 near surface concentration fields, given by the numerical solution, rates of mass
transfer from the surface are computed and expressed in the form of a Sherwood number (Sh). The
dependence between Sh and the Peclet number for flow past the surface is then established for each
of the flow geometries.
Finally, equations are derived for the concentration contour surfaces at a large distance from the
soluble solids, by substituting the information obtained on mass transfer rates in the equation
describing solute spreading in uniform flow past a point (or line) source.
ER -