Effects of Data Conditioning on Mass and Drag Coefficients

Abstract

The effects of data conditioning on the mass and drag coefficients (Cm & Cd) are reviewed by two geometric and one numerical interpretations. Two geometric analyses of data conditioning proposed by Dean demonstrate that when the Dean eccentricity parameter E equals unity, the data are equally well-conditioned for determining Cm & Cd. For simple harmonic data, the Dean eccentricity parameter may be shown to be proportional to the Keulegan-Carpenter parameter, K; ie., E=4K/2ir2. When E 1.0, then K=11.40 and the Dean error ellipse is a circle with zero eccentricity. The matrix condition number of the 2 x 2 matrix used to determine Cm & Cd in a best leastsquares sense becomes unity when K=13.16 and E=1.15. Two sets of experimental data are compared with the two geometric and one numerical analyses.