Direct numerical simulation of flow in a ribbed channel

The issue of turbine lifetime is an important one, particularly for modern turbines operating at high temperature regimes. A cooling design such as ri bs may achieve an improved lifetime and complex mechanisms of heat transfer need to be well studied. In this paper, a Direct Numerical Simulation (DNS ) is presented for a 3-D channel flow with two square ribs on the lower wal l. The full unsteady compressible Navier-Stokes equations are solved with a n original hybrid finite difference/finite element scheme. The Reynolds num ber of the simulation is 7 000 based on the bulk velocity at the inlet and the channel height. The present study is mainly devoted to understand the m echanism of heat transfer at the wall through the topological analysis of t he flow and the temperature flux. Results show that the large-scale structu res generated by obstacles splash onto the lower surface and induce longitu dinal vortices which enhance heat transfer at the wall. A comprehensive dat a base including 56 correlations was set up for testing and improving turbu lence models for this complex, separated flow.