A direct numerical simulation of transition in mixed convection flows between two heated parallel plates

Abstract

This paper seeks to increase our understanding on the fluid mechanics and heat transfer in a transitional mixed convection flow between two vertical plates. Direct numerical simulation by the spectral method, with a weak formulation, is used to solve the transient 3–D Navier‐Stokes equations and energy equation. Initial disturbances consist of the finite‐amplitude 2–D Tollmien‐Schlichting wave and two 3–D oblique waves. The transition phenomena in a mixed‐convection flow can be significantly different from the isothermal flow. Disturbance competitions among different modes are also found to be different from those known for an isothermal flow. In a mixed‐convection flow, there exist thresholds for the low‐mode Fourier waves. The intensified vortices are concentrated left of the central surface between the two plates. Hairpin vortices are formed with high Ri. Based on the flow visualization, the λ vortices are found to be staggered on the surfaces parallel to the plates. The Ri number seems to be the main parameter governing the transition mechanism. The Nu number is found to increase during transition.

Citation

Hao, C.C. and Chung, J.N. (1995), "A direct numerical simulation of transition in mixed convection flows between two heated parallel plates", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 5 No. 5, pp. 399-422. https://doi.org/10.1108/EUM0000000004071