Abstract
We studied fully developed pipe flow of fibre-laden aqueous foams and decoupled their bulk rheological properties boundary effects like slippage at the pipe wall. The air volume fraction of the foams varied between 70% and 75%. The addition of hardwood fibres at the consistency 20 g/kg to plain aqueous foam increased viscosity more than 100%, while with microfibrillated cellulose at a consistency of 25 g/kg the increase was about 30%. The effect of synthetic (cellulosic)rayon fibres was negligible at the consistency of 20 g/kg. All the studied foams could be described as shear-thinning power-law fluids with significant slippage at the pipe wall by particles size and interactions between particles and bubbles.
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