ISSN Online: 2377-424X
ISBN Print: 978-1-56700-474-8
ISBN Online: 978-1-56700-473-1
International Heat Transfer Conference 16
DIRECT NUMERICAL SIMULATION OF A TEMPORALLY DEVELOPING NATURAL CONVECTION BOUNDARY LAYER ON A DOUBLY-INFINITE ISOTHERMAL WALL
摘要
The present study employs a direct numerical simulation (DNS) to observe and analyze the laminar-turbulent transition of an unsteady temporally developing (periodic) natural convection flow along a vertical isothermal wall. The power law correlation for the wall shear stress and the Nusselt number for the temporally developing flow in the spatially turbulent regime is similar to the spatially developing flow: τw, Nu ~ CGrm, where
m = −2/9 for the wall shear stress correlation and m = 1/3 for the Nusselt number correlation. The
development of this temporally developing boundary layer shows different characteristics from a spatially developing boundary layer which originates from a leading edge. In spatially developing flows, stream-wise modes roll up to form Λ-shaped three-dimensional structures, whereas in the temporally developing flow convective rolls are ejected from two-dimensional Tollmien-Schlichting waves prior to the formation of Λ-shaped vortices.