Measuring power laws is hard! Fortunately, Newtonian fluids are well behaved.
J.A. Dijksman, S. Mukhopadhyay, C. Gaebler, T.P. Witelski, R.P. Behringer — Physical Review. E, Statistical nonlinear, and soft matter physics 92 (2015)
Obtaining self-similar scalings in focusing flows
MultiPhase Matters 