Accession Number : AD0714539

Title :   Evaluation of Quasi-Steady Approximation for Viscous Effects in Unsteady Liquid Pipe Flow,

Corporate Author : KENTUCKY UNIV LEXINGTON

Personal Author(s) : Wood,D. J. ; Kao,T. Y.

Report Date : 24 JAN 1968

Pagination or Media Count : 8

Abstract : Usage of the quasi-steady square law approximation for viscous effects in unsteady one-dimensional turbulent pipe flow is questioned. This approximation which presently is employed in some manner in most unsteady turbulent flow calculations is utilized to compute the attenuation of a pressure wave generated by rapid closure of a down-stream terminal valve in a flow system. It is shown that observed values for viscous attenuation may be several times greater than those obtained utilizing the quasi-steady analysis. The possibility of utilizing a dynamically determined friction factor in the quasi-steady analysis also is investigated and shown to yield inconsistent results. It is concluded that for severe case of unsteadiness associated with pressure surges the quasi-steady approximation is inadequate. Because of significant changes of velocity distributions in most unsteady flow situations the use of a quasi-steady approximation is not supported for unsteady flow calculations. (Author)

Descriptors :   (*ONE DIMENSIONAL FLOW, PIPES), APPROXIMATION(MATHEMATICS), VISCOSITY, LIQUIDS, TURBULENCE, ATTENUATION

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE