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.
Vortex shedding from a bluff body is a classical problem as well as an exciting challenge for fluid mechanics. Since the time of Prof. Strouhal at the end of the 19th century, the phenomenon has been frequently studied by several generations of researchers. This contribution introduces (1) the historical contest of the milestone studies, (2) motivations and goals of the recent investigations, and (3) recent original results of research on the fluid dynamics and heat transfer of heated and cooled circular cylinders in the cross-flow, obtained mainly in the Institute of Thermomechanics. and Obsahuje seznam literatury