Mixed convection from an elliptic tube placed in a fluctuating free stream

Heat transfer from an inclined elliptic tube in a convective environment with fluctuations in the free-stream velocity is investigated numerically including the effect of buoyancy forces. The free-stream direction is horizontal and normal to the tube axis and the flow field is essentially two-dimensional. The investigation is based on a numerical solution of the conservation equations of mass, momentum and energy. The study focuses on the effect of amplitude and frequency of fluctuations on the heat transfer process. The time-average of the Nusselt number is found to increase with increasing amplitude of the fluctuations and with decreasing frequency. Details of the velocity and thermal fields are presented in the form of isotherms and streamline patterns in addition to the surface vorticity and local Nusselt number distributions.