Chapter 5 - Forced convection

Abstract

This chapter builds on the foundations laid in Chapter 4. The chapter starts off with Prandtl’s boundary layer simplifications that lead us to the simplified boundary layer equations for flow and heat transfer over a fundamental geometry like the horizontal flat plate. Following this, the nondimensionalization of the governing equations, through which the key dimensionless parameters like Reynolds number, Prandtl number, and Nusselt number are identified is presented. After this, approximate solutions to the boundary layer equations are presented through the powerful integral method. External forced convection from other geometries like cylinder, sphere, and rows of tubes is briefly presented next, followed by an introduction to basic ideas in turbulent flow and heat transfer. The extremely useful and equally potent Reynolds analogy is then introduced. The chapter then moves on to internal flows where the governing equations are developed. A key idea in internal flow, namely, bulk mean temperature, is introduced, and by employing this idea, the concept of fully developed flow is established. Following this, an analytical solution for fully developed flow and Nusselt number for a constant heat flux for a hydrodynamically and thermal fully developed flow is presented. The chapter ends with the listing of a few popularly used correlations for turbulent flows inside tubes and ducts.