A number of correlations for friction factor determinations in smooth pipes have been proposed in the past decades. The accuracy and applicability of these friction factor formulas should be examined. Based on this notion the paper is designed to provide a comparative study of friction factor correlations in smooth pipes for all flow regimes of Bingham fluids. Nine models were chosen. The comparisons of the selected equations with the existing experimental results, which are available in the literature, were expressed through MARE, MRE+ , MRE- , RMSE, Ѳ, and S. The statistical comparisons were also carried out using MSC and AIC. The analyses show that the Wilson-Thomas (1985) and Morrison (2013) models are best fit models to the experimental data for the Reynolds number up to 40000. Within this range, both models can be used alternately. But beyond this Re value the discrepancy of the Wilson-Thomas model is higher than the Morrison model. In view of the fact that the Morrison model requires fewer calculations and parameters as well as a single equation is used to compute the friction factor for all flow regimes, it is the authors’ advice to use this model for friction factor estimation for the flow of Bingham fluids in smooth pipes as an alternative to the Moody chart and other implicit formulae.
Concentration and particle size distribution has been experimentally measured in a 2D rectangular duct under near iso-kinetic conditions for multi-sized particulate slurry. Measurements have been made at different flow velocities for various efflux concentrations in the range of 10 to 50 % by weight. It is observed that the concentration profile is highly skewed towards the bottom of the duct, which reduces with increase in efflux concentration and velocity. Similar phenomenon is observed in the distribution of individual particle size fractions with the effect being more pronounced for the coarser particles. and Rozdělení koncentrace a velikosti částic bylo měřeno ve 2D pravoúhlém kanále při proudění disperze různě velkých částic za téměř iso-kinetických podmínek. Experimenty byly provedeny při různých rychlostech s dopravními koncentracemi v rozsahu 10 až 50 hmotnostních procent. Bylo zjištěno, že koncentrační profil je výrazně zešikmený ke dnu kanálu, což se však zmenšuje s růstem koncentrace a rychlosti. Podobný jev byl pozorován u distribuce částic jednotlivých velikostních frakcí. Jev se projevuje tím výrazněji, čím větší jsou částice.