This experimental and analytical investigation considers the potential heat transfer enhancement from resonant excitation of the shear-layer instability in a ribbed duct flow. The specific interest is in the degree of excitation-induced enhancement for various flow and geometrical conditions resulting from external acoustic source excitation. The timewise evolution of the local wall heat transfer will be measured and linked to the instantaneous flow behavior. The complementary numerical study will assess the modeling capabilities and extend the experimental parameter range. The enhancement of heat transfer is important in many applications including electronics cooling and heat exchanger design. This research addresses heat transfer augmentation through the coupling of an external excitation and flow instability. The enhancement by flow instability has been documented so that the new part of this research is the use of external excitation. There is a potential for significant enhancement by this technique.