Binormal cooling errors in crossed hot-wire measurements

In crossed hot-wire measurements, cooling of the filament in the direction normal to the hot-wire measurement plane will cause additional heat transfer, called binormal cooling. It is shown that binormal cooling can lead to significant errors in measuring the mean velocity and the turbulence levels in regions where the turbulence level is high, such as the near-wall region of pipes and boundary layers. In a near-wall measurement of a pipe flow, binormal cooling effects lead to errors up to 1.5% in mean velocity and 4% in turbulent shear stress.