Berdnyk O. Modeling fluid mechanics phenomena in tubes with easily penetrable roughness

Mathematical models for pressure-driven incompressible viscous tube flows with easily penetrable roughness (EPR) near wall or in the middle have been suggested. Influence of EPR height and density on the flow properties in round, elliptical and rectangular tubes, as well as convective heat transfer in the round tube were investigated. Dependences of hydraulic resistance coefficient on Re number have been generalized for accounting the EPR characteristics. The Prandtl's turbulent mixing length hypothesis has been generalized for the case of EPR near wall. As a result, a performance algorithm is obtaines for the flow, shear and heat exchange in ducts with the EPR useful for forecasting optimal flow regimes in such tubes.