Fig. 2. Variation in rotational coefficient (Crot,exp) with
angular velocity and axis of rotation. (A) Rotational coefficients
versus angular velocity (
; rad s-1) for each axis
of rotation. The axes of rotation used for each series of measurements are
given in blue. Non-dimensional values of angular velocity
(
) are presented in red under the
corresponding dimensional value. The vertical dashed lines signify the section
through this plot at values of
of 0.166 and 0.374, for which the representative regressions are provided in
B. 
, non-dimensional axis
of rotation. (B) Rotational coefficient versus axis of rotation. Two
representative plots of rotational force coefficients at two values of
, 0.166 (filled circles) and
0.374 (open circles), are plotted, with the corresponding regression lines for
each. The red line indicates the prediction given by equation 9. (C) A series
of regression lines for representative values of angular velocity (numbers in
blue) plotted together with the quasi-steady prediction (red line) from
equation 9.