The voidage function for the drag force ratio in a liquid-fluidized bed


  • Norman Epstein

In my R&D Note entitled “The Voidage Function for the Drag Force Ratio in a Liquid-Fluidized Bed,” Can. J. Chem. Eng. 83, 566–572 (2005), I stated that the equation

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relating the drag coefficient CDS for an isolated sphere to the particle Reynolds Number Re at Re < 3000 had been “mistakenly attributed to Dallavalle (1948)” by several authors in the literature. I made this statement on what I thought was a careful page-by-page scanning of “Micromeritics: the Technology of Fine Particles,” 2nd Edition, by J. M. Dallavalle, Pitman Publishing Corp., New York (1948), which was one of the textbooks that we used at New York University in John Happel's 1948–49 graduate course in particle dynamics. I have just flipped the pages of that dog-eared book again and, to my astonishment, I found precisely the above equation on page 23 (Equation 2.14). I apologize to all those authors whom I cited as having misattributed that equation to Dallavalle. They were right. I was wrong.

Norman Epstein

September 4, 2008