Theoretical Discussions on Oscillating Heat Transfer Performance in Small Ducts

A theoretical investigation was conducted to understand the temperature fluctuation corresponding to a typical perturbation velocity of sinusoidal oscillation in small ducts or small staggered ducts, and an emphasis was addressed on the characteristics of temperature fluctuation in a two-dimensional system. For a very small temperature fluctuation or flow oscillation at very large frequency, the local temperature fluctuates with the same frequency as the flow oscillation, and can be divided into two parts, each one caused by the flow oscillation in one flow direction. Normally the temperature fluctuation is directly proportional to the flow oscillation amplitude and the time average temperature gradient, and inversely proportional to the flow oscillation frequency. And the temperature fluctuation has nearly a phase angular difference close to π/2 with respect to velocity oscillation.