Mass transfer from a vertical flat plate due to a constant upward flow

Abstract

Subject classification 76R50 76R05 76M45 76D10This paper examines the mass transfer from the vertical flat surface of a soluble material due to a constant upward flow. The mass transfer rate due to this upward flow is calculated and used to obtain the distance along the surface at which the boundary layer separates. For relatively large velocities no separation will occur and the solution approaches that of forced convection on a horizontal surface.

A mathematical analysis of drug dissolution in the USP flow through apparatus

“…Equation (12) is applied to the surface of a compact for several small velocities and table (3) compares the results with that of natural convection. [3] shows that for small velocities the boundary layer formed due to an upward flow separates due to the weight of solution containing dissolved drug. However, for sufficiently large upward velocities boundary layer separation will not occur across the height of the surface and the solution will approach that of horizontal flat plate flow.…”

“…At some height along the surface the weight of solution containing the dissolved drug counteracts the upward force causing boundary layer separation. McDonnell et al [3] have examined this case using a modified flat plate Blasius flow based on the work of Lévêque [16]. The flux per unit width is given as…”

“…However, for sufficiently large upward velocities boundary layer separation will not occur across the height of the surface and the solution will approach that of horizontal flat plate flow. The criterion to prevent separation occurring is given by McDonnell et al [3] as F r > 0.071, where F r is the non-dimensional Froude number. The required upward velocity may be calculated using…”