Abstract
In their recent topical review, Nabavi and Siddiqui (Meas. Sci. Technol. 2010 21 042002) recommended the use of hot-wire anemometry for velocity measurements in pulsating flows, especially at high frequency. This recommendation is misleading. The procedures invoked by these authors are valid only for small-amplitude fluctuations, which are of little interest for pulsating flows. When large-amplitude velocity changes occur without flow reversal, new procedures for the correction of the nonlinearities of the hot wire are required. This case was thoroughly investigated for a constant-voltage anemometer by Berson et al (Rev. Sci. Instrum. 2009 80 045102). In addition, we show that when flow reversal occurs—a case most relevant to pulsating flows—accurate hot-wire velocity measurements are not possible because heat transfer is not well defined when velocity passes through zero and changes direction.
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