Features of the Transition from Laminar to Turbulent Flow in the Presence of Non-Isothermal Conditions in Tubes

The features of the transition process in a tube from laminar to turbulent flow were investigated as a function of various factors. The initiation and development of vortex structures were studied under conditions of flow non-isothermality for a fluid with a strong temperature dependence of dynamic viscosity. Differences in the stages of transition were analyzed for cases with a positive viscosity gradient in the near-wall region compared to cases with a negative viscosity gradient or constant viscosity. An acceleration of the transition process with increasing flow velocity (Reynolds number) was demonstrated. The possibility of controlling the transition process through partial surface structuring was also analyzed.