Heat transfer enhancement by flow destabilization in electronic chip configurations

Numerical simulations of the flow pattern and forced convective heat transfer in geometries such as those encountered in cooling systems for electronic devices are presented. For Reynolds numbers above the critical one, these flows exhibit a traveling-wave structure with laminar self-sustained oscillations at the least-stable Tollman-Schlichting mode frequency. Three techniques of heat transfer enhancement by flow destabilization in grooved channels are compared on an equal pumping power basis: active flow modulation, passive flow modulation, and supercritical flow destabilization. It is found that the best enhancement system regarding minimum power dissipation corresponds to passive flow modulation in the range of low Nusselt numbers. However, supercritical flow destabilization becomes competitive as the requirement for higher Nusselt numbers begins to dominate the design choices. The hydrodynamic heat transfer numerical results are obtained by direct simulation of the unaveraged energy and Navier-Stokes equations using a spectral-element-Fourier method for the spatial discretization. It is shown that computational heat transfer and, in particular, direct numerical simulation using advanced numerical schemes can contribute significantly in exploring the physics associated with heat transfer enhancement by flow destabilization