Predicting laminar–turbulent transition in Poiseuille pipe flow for non-Newtonian fluids

We present a new phenomenological approach for quantifying laminar–turbulent transition in pipe flow. This criterion is based on averaging a local Reynolds number to give ReGReG. Our localised parameter shows strong radial variations that are maximal at approximately the radial positions where puffs first appear during the first stages of turbulent transition. We present comparative data for experiments conducted with Glycerin, Xanthan and Carbopol solutions, each of which serves to demonstrate the validity of our approach.