Flow and heat transfer in curved wall jets on circular surfaces

Consideration is given to curved wall jets (i.e. flow along a wall which is curved in the streamwise direction) and, in particular, to flow along either a convex or a concave circular surface. The laminar flow and heat-transfer characteristics are investigated by making use of the method of inner and outer expansions. The Navier-Stokes and energy equations are expanded in series, with 1 √ Re as the expansion parameter. The first-order equations are identical to the conventional boundary-layer equations, whereas the second-order equations are corrections for curváture and displacement effects. The latter equations were solved by a difference-differential method, with Pr = 0·72 for the energy equation. The second-order correction increases the wall shear, the extent of the increase being greater for flow over a concave surface than for flow over a convex surface. On the other hand, the second-order correction either increases or decreases the Nusselt number, depending on whether the surface is convex or concave. The Coanda effect, whereby an induced transverse pressure difference inhibits flow separation, was demonstrated by the analysis.