Technical Note:Conditions for Similarity of Mass-Transfer Coefficients and Fluid Shear Stresses between the Rotating Cylinder Electrode and Pipe

Abstract

Abstract A debate surrounds the question of whether to use equality of the mass-transfer coefficient or of the fluid shear stress at the wall to define flow parameters to simulate velocity-sensitive corrosion between geometries. In principle, this debate may be circumvented if both parameters could be simultaneously similar in the modeled and modeling geometries. To explore this possibility, an equation derived from the analogy among heat, mass, and momentum transfer was used to estimate rotating cylinder electrode diameters and rotation rates that enable simultaneous similarity of the mass-transfer coefficient and the shear stress at the wall between hydraulically smooth cylinders and straight pipes. The results imply that under some but not all conditions, practical cylinder diameters and rotation rates may be found.