Accession Number : AD0715231

Title :   A Method for Converting the British Circle C Coefficient Based on the Froude 'O' Values to a Circle C Coefficient Based on the Schoenherr Formula. Second Edition,

Corporate Author : DAVID TAYLOR MODEL BASIN WASHINGTON D C

Personal Author(s) : Gertler,Morton

Report Date : JUN 1949

Pagination or Media Count : 8

Abstract : For many years it has been the practice of the British model basins to use the so-called circle coefficients for presenting comparative resistance data. These circle coefficients, are based on Froude's original notation in which the dimensions are expressed in terms of the unit U, which is equal to the length of a side of a cube whose volume is equal to the volume of a given ship. The circle coefficient most commonly used as a resistance parameter, known as circle C, is generally calculated from the resistance or effective horsepower of a given ship as predicted from model-test data using the R.E. Froude frictional constants for both model and full scale. For comparative purposes, the circle C values for the various vessels are generally given for a 400-foot ship operating in salt water of 59F. A proposal was to adopt the Schoenherr frictional-resistance formulation, which is used by all American model basins, for use internationally. One of the consequences of such a proposed change is that the numerical values of circle C calculated with the Schoenherr formula differ from those calculated with the Froude constants. A method for easily converting circle C based on the Froude constants to circle C based on the Schoenherr formula is derived and presented. For brevity, these coefficients are referred to as the Froude circle C and the Schoenherr circle C, respectively. (Author)

Descriptors :   (*SHIPS, SKIN FRICTION), SHIP MODELS, SEA WATER, FLUID FLOW, MATHEMATICAL ANALYSIS

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE