Flow and heat transfer from a single cylinder that forms a part of an in-line array has been numerically analyzed under oscillatory flow conditions. The cylinder is a phospher-bronze wire, while the fluid is air. The flow and the thermal fields depend on the extent of blockage, parameterized by the porosity. Calculations have been reported in the present study mainly for a porosity of 0.71. Reynolds numbers of up to 20 based on the cylinder diameter have been employed in the calculations. Navier-Stokes equations are utilized for the gaseous phase, while the thermal problem involves conjugate heat transfer between the fluid and the solid. The flow field is determined using a harmonic analysis formulation, while the temperature field is obtained by marching in time. Numerical results of the present study show that the variation of friction factor with Reynolds number for oscillatory flow has a trend similar to that of steady flow. In this respect, frequency has a secondary role in determining friction factor. The first wire of the array has a higher friction factor compared to the developed section of the array. Inertial effects appear first in the third harmonic of the flow field. When the metallic wire is subjected to heating alone, the steady flow Nusselt number increases with Reynolds number. The Nusselt number also increases with the forcing frequency. The influence of flow development on heat transfer is found to be small. The local variation of dimensionless heat flux over the wire surface is qualitatively similar to that for steady flow, once the flow-direction is taken into account. Simulation with hot and cold fluid alternately moving past the wire reveals the following: The reciprocal of the twice the time constant of the gas-wire system is a characteristic frequency that determines the extent of energy exchange between the wire and the gas. When the frequency of the pulsating flow is matched with this value, the separation of the maximum and minimum tem- peratures attained by the wire is seen to be the greatest. As the forcing frequency increases, the duration of the transients increase and steady state is delayed. The effectiveness of energy transfer between the wire and the fluid decreases at higher Reynolds numbers.
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