Experimental study and predictions of pressure losses of fluids modeled as Herschel–Bulkley in concentric and eccentric annuli in laminar, transitional and turbulent flows

Experimental data is presented for the flow of bentonite–water dispersions, modeled as Herschel–Bulkley fluids, for the pressure loss at different flow rates covering laminar, transitional and turbulent flow regimes, while flowing in concentric and fully eccentric annuli. The concentric experimental data has been compared with predictions from a recently-introduced model which covers the full flow regimes for concentric annulus, while corrections for eccentricity, previously suggested for non-Newtonian fluids, have also been used to compare with eccentric data. Laminar flow data not only from this work but also from work from the literature is very well predicted while transitional and turbulent flow data are predicted with less accuracy, requiring improvements on predicting transition points. The corrections for eccentricity work well and can be used to accurately correct concentric annulus data. Turbulent non-Newtonian flow data exhibit a power law exponent relationship between flow rate and pressure loss smaller than the Newtonian case pointing out directions for future research.

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► We present flow data of Herschel-Bulkley fluids in concentric and eccentric annuli.
► Kelessidis et al. model (Founargiotakis et al., 2008) predicts well fluid pressures.
► The API model overpredicts pressures in transitional and turbulent flows.
► Further work is needed for determining points of transition.