In the attempt to develop the novel core element for plate-type heat exchanger, this study examines the flow and heat transfer phenomena in a narrow convergent-divergent wavy channel with sinusoidal wall-waves inclined at 45 degrees to the direction of main flow. Detailed heat transfer distributions over the wavy wall are measured using the steady-state infrared thermography methods. Turbulent flow phenomena in this wavy channel are analyzed using the numerical results predicted by Star-CD software. Numerical results are validated by comparing the calculated and experimental pressure-drop coefficients. Experimental heat transfer data and the calculated flow structures are cross examined to disclose the mechanism of heat transfer enhancement (HTE) in this wavy channel. Thermal performance factors for this wavy channel with turbulent flows are compared with other HET measures based on the results calculated from the empirical heat transfer and pressure drop coefficients, which enlightens the competitive advantage of this wavy channel for engineering applications.