Accession Number : AD0810351

Title :   KINETIC THEORY OF THE AERODYNAMIC DRAG OF A SLOWLY ROTATING SPHERE.

Descriptive Note : Technical rept.,

Corporate Author : CALIFORNIA UNIV BERKELEY DIV OF AERONAUTICAL SCIENCES

Personal Author(s) : Willis, D. Roger

Report Date : JAN 1967

Pagination or Media Count : 16

Abstract : The drag of a sphere rotating slowly inside a concentric stationary sphere is analyzed for a range of values of the mean free path in the gas filling the space between the spheres. Knudsen iteration is used to predict the drag for high values of the Knudsen number, based on the ratio used to represent the gas phase collisions. Based on this result and that appropriate for slip flows (low Knudsen number) two interpolation formulas are suggested to predict the drag for arbitrary Knudsen number. The predictions from these formulas agree well with available experimental data. A solution of the problem, using the moment method proposed by Lees, Leads to a simple algebraic expression for the drag which is not in such good agreement with the data. (Author)

Descriptors :   (*DRAG, KINETIC THEORY), (*SPHERES, ROTATION), (*BOUNDARY LAYER, DRAG), KNUDSEN NUMBER, ITERATIONS, PROBLEM SOLVING, MATHEMATICAL PREDICTION, FLOW FIELDS, GAS FLOW, MOLECULAR PROPERTIES, MATHEMATICAL MODELS, STATISTICAL PROCESSES, SCATTERING.

Subject Categories : Fluid Mechanics
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE