The influence of oscillation and heat transfer on the lift and drag coefficients over a circular cylinder is numerically studied in this work. Temperature difference of 300, 600 and 900 K is used between the cylinder wall and the incoming fluid flow for Reynolds number of 100. Air is used as the fluid and the temperature dependent properties of air are used for the analysis as a significant change in the properties of air incurred. Numerical simulation is done on Ansys/fluent with O-type mesh and the vibration in the circular cylinder is induced using user defined function. The vibration of the cylinder in streamwise direction is induced at a frequency ratio of 0.5, 1, and 2, with the natural frequency of the cylinder being 2.5 Hz marking its Strouhal number. It is observed that for all the induced frequencies, the forcing function interacts with the natural frequency of the system, and the beating phenomenon spectrum is observed, where two distinct frequencies appear which correspond to the sum and difference between the natural and the forcing frequency. At the frequency ratio of 0.5 (1.25 Hz), the spectrum of lift coefficient is characterized with three peaks centered at 2.5 Hz (natural frequency), 3.75 Hz (sum) and 1.25 Hz (difference). Oscillating the isothermal cylinder at a frequency ratio of 0.5 caused a negligible increase in the rms value of the lift coefficient by 2.13%, drag coefficient by 0.17%, and had no effect on the natural frequency of the system, however at a frequency ratio of 2, a drastic increase in the rms value of lift coefficient by 137.4% and drag coefficient by 13.9% occurred, indicating the lock-on regime. As compared to the stationary isothermal cylinder, heating the cylinder 300K above the incoming flow, decreased the rms value of the lift coefficient by 62.7% and the natural frequency by 16%, while increased the drag coefficient by 7.3%. The results show that heating of cylinder in cross-flow is equivalent to running the flow at a reduced Reynolds number and in the laminar region, this is associated with lower Strouhal number and lower amplitude of lift but a higher drag.

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