Heat transfer from a cylinder in a time-dependent cross flow at low Peclet number

The heat transfer from a constant-temperature cylinder in a uniform, time-dependent cross flow at low Peclet number is considered. The time dependence is allowed to be strong, so that the velocity fluctuations may be comparable to, or larger than, the mean flow. The first nontrivial term in the Oseen approximation is calculated using matched-expansion theory, and its physical significance is discussed. As an illustration, the time-dependent heat transfer is calculated for a steady cross flow with large sinusoidal perturbations.