Investigation of the stabilezed flow of pseudoplastic liquid, described by the Sisko model, in the cylindrical tube

O. V. Matvienko

Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mehanika, no. 55 (2018), pp. 99-112

Résumé

The pseudoplastic fluid flow described by the Sisko model was investigated, the dependence of the fluid flow rate on the pressure drop and also radial distribution of the velocity and the effective viscosity of the flow were determined. The effective viscosity of the flow is directly proportional to the viscosity at an infinite shear rate and depends nonlinearly on the Sisko number. In the peripheral and near-wall part of the flow, the effective viscosity is characterized by low values. However, in the vicinity of the flow axis, where the velocity gradient has low values, a significant increasing the effective viscosity is observed. As the shear rate increases, the effective viscosity decreases. With an increase in the consistency of the fluid and the viscosity at an infinite shear rate, the value of the average viscosity increases. This effect is most pronounced for low-velocity flows moving at a small pressure drop. The investigations carried out have shown that for values of the Sisko number less then 500 the non-Newtonian properties of the flow appear insignificantly and with an accuracy sufficient for engineering calculations, one can consider the flow of a Newtonian fluid. The coefficient of hydraulic resistance of a pseudo-plastic Sisko fluid is significantly larger than the resistance coefficient of a Newtonian fluid with a viscosity $\mu_\infty$ moving under the same pressure drop.

Détail

Keywords: rheology, pseudoplastic media, viscosity, non-Newtonian fluids, the Sisko model.