Gravitational and centrifugal buoyancy effects in curved square channels with conjugated boundary conditions

Fully developed laminar flow in a curved square channel with peripheral wall conduction is examined. The wall average Nusselt number, Nu, is presented as a function of four parameters: the wall conduction parameter, φ, the Prandtl number, and two Grashof numbers, Grg and Grc, which represent the gravitational and centrifugal forces, respectively, present in a variable density fluid. Numerical solutions are presented for 4.4 < De < 210.9, 0.01 < φ < 20.0, and 0.01 < Pr < 7.2. For constant De, curved channel mixed convection Nu values are demonstrated to be reduced below the curved channel forced convection values due to a weakening of the secondary flow field. A curve illustrating the relationship between φeff, defined as the value of φ at which a constant wall temperature boundary condition can be assumed, and De is presented.