Author(s): M. M. Gibson; T. Dakos

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Abstract: A basic experiment in turbulent heat transfer is that in which a uniform temperature gradient issuperposed on decaying near'y-isotropic grid turbulence_in a constant-velocity stream.It wasfirst performed by the late Ken Wiskind who found,as Corrsin(1952)had predicted,that thetemperature gradient would maintain itself,and that the interaction of the gradient with theturbulence would produce temperature fluctuations increasing indefinitely with time,or distancefrom the grid.Following Wiskind's(1962)pioneering experiment,additional studies by Alexo-poulos and Keffer(1971),Venkataramani and Chevray(1977),Sirivat and Warhaft(1983),and Budwig,Tavoularis and Corrsin(1985)have further confirmed Corrsin's hypothesis and,by adding more detail,have improved understanding.The flow is just about the simplest problemin turbulent convection that can possibly be imagined.But it s of special interest to theo-reticians because the governing equations are so simplified that it s possible to isolate andexamine difficult terms.Results from this experiment ought to be useful n formulating andtesting turbulence closure models.However,only the data from the last two papers cited aresufficiently extensive,and these show such unexplained differences as to warrant further exper-imentation.The present experiment was designed specifically to provide data at higher Reynoldsnumbers and,in order to reduce persisting effects of the initial conditions,at greater distancesfrom the grid,than had been attempted before.

DOI:

Year: 1991