Laminar‐turbulent transition for low Reynolds number mixed convection in a uniformly heated vertical tube Available to Purchase

Upward mixed convection flow of air in a uniformly heated vertical tube was studied numerically using the three‐dimensional elliptic conservation equations and the Launder and Sharma low Reynolds number k–ε turbulence model. For Re=1,000 the fully developed flow field undergoes two transitions as the Grashof number increases: thus, this flow field is laminar for Gr<8×10⁶, turbulent for 8×10⁶<Gr<5×10⁷ and again laminar for Gr>5×10⁷. In the entry region, turbulent kinetic energy decays monotonically for Gr≤3×10⁶ and Gr≥7.1×10⁷. For Gr between these two values it initially increases from the imposed inlet condition and then decreases towards its calculated fully developed value. The mean velocity profiles as well as the axial evolution of the skin friction coefficient are presented for representative values of Gr.