Probability densities of v_r for QK(q = 1.9) configuration at Re ≈ 2.2 × 10⁴ using water-glycerol mixture (top panel, labelled A in Fig. 10), QK(q = 1.9) configuration at Re ≈ 3.3 × 10⁵ using water (middle panel, labelled B in Fig. 10), and solid-body rotation (bottom). Apparently larger standard deviations in the solid body flow (C) than those in the QK flow in water (B) are due to the larger Ω_OC in the flow (C). The curves are Gaussian fits to the data, vertical lines are first, second and third standard deviations from their means . The data were acquired at z = 75 mm. Note that non-Guassian tails at the level of ≈ 0.2 are due to acrylic optical defects and not genuine characteristics of the flows.