Abstract
The effective length for spatial resolution of a hot-wire sensor has been shown by the author's previous paper, to be around 2/3 of its geometrical length provided that the nondimensionalized length is of order 3 or less. The result is, however, limited to velocity fluctuations centered at the center of the wire. In this paper, analysis is extended to randomly located fluctuations. With the assumption that fluctuations are spatially sinusoidal, the power spectral output of a hot-wire sensor is shown to decrease with the wire-length to wave-length ratio, with rates the smaller for the shorter (in nondimensionalized value) wire. In this sense, the effective length of a sensor wire with the nondimensional length less than 3 is found again to be about 2/3 of its geometrical length.
