ABSTRACT
This chapter reviews the flow regimes and size-based miniature flow passage categories and discusses the limitations of the classical convection heat and mass transfer theory with respect to its application to miniature flow passages. The classical convection theory is based on modeling the fluids as continua throughout the flow field. Since fluids are made of molecules, the applicability of the continuum-based treatment of fluids is the most obvious issue with respect to the classification of miniature flow passages. The common practice in modeling conventional flow systems is to assume no-slip as well as thermal equilibrium conditions at a solid–fluid interface. The chapter discusses the Couette flow model for flow without velocity slip and temperature jump. The effect of surface roughness has been found to be significant in small flow passages, even in the laminar flow regime. The chapter also reviews the basics of electrokinetics and electroosmosis.
