Chapter 5 - Convective flow in buoyant plumes and jets

Abstract

Free and mixed convection flows arising from point and line thermal sources at the leading edge of a vertical surface, also referred to as a wall plume, in an infinite expanse of an otherwise quiescent fluid are of considerable interest for both theoretical and practical purposes. This chapter reviews some aspects of buoyant plumes arising from heated point or line sources. A point heat source of buoyancy in an unbounded fluid can give rise to free convection in the form of a narrow vertical plume. Most plumes in common experience are turbulent but there are circumstances, typically when the fluid viscosity is large, in which a plume remains laminar for a considerable height. The three-dimensional wall plumes arising from localized heat sources are of even greater practical importance than their two-dimensional analogues because real heat sources are of finite size. In particular, these plumes are relevant to the cooling of electronic components in circuit boards. The chapter also explains the mechanism of laminar plane buoyant jets.