The relative contribution to the radiometric force of the area and perimeter of the vane is studied experimentally and numerically. Experimentally, a circular vane, a low-aspect rectangular vane, and a high-aspect rectangular vane were all tested on a force balance, with nano-Newton resolution, placed in a stagnant gas. The computational results were obtained through 2-D simulations using the direct simulation Monte Carlo method, as well as a discrete ordinate solution of the ES model kinetic equation. Gas pressure was varied from 0.006 to 6 Pa, which was a broad enough range to observe the characteristic peak force production of a radiometer in the transition regime, where the peak occurs at Kn ~ 0.1. It was found that the area of a radiometer vane is responsible for a significant amount ofthe total force production through a wide range of operating pressures. It is only at the highest background pressures, well after force production has peaked, that the vane perimeter appears to dominate the operation of the radiometer.


Copyright (2008) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in (N.P. Selden, S.F. Gimelshein, E.P. Muntz, A. Alexeenko, and A.D. Ketsdever, “Experimental and Computational Study of Area and Perimeter Contributions to Radiometer Forces,” 26th International Symposium on Rarefied Gas Dynamics, Kyoto, Japan, July 20-25, 2008.) and may be found at http://dx.doi.org/10.1063/1.3076616. The following article has been submitted to/accepted by [American Institute of Physics]. After it is published, it will be found at (http://dx.doi.org/10.1063/1.3076616). Copyright (2008) N.P. Selden, S.F. Gimelshein, E.P. Muntz, A. Alexeenko, and A.D. Ketsdever. This article is distributed under a Creative Commons Attribution 3.0 Unported License.

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