Dobroljubova street 2, 29, Pavlograd, Dnjepropetrovsk region, 51400 Ukraine
The identification of stream in the straight pipe as a flexible rod has allowed to present the criterion expression for determination of transition of the laminar flow to the turbulent as a loss of stability of the rectilinear static structure of translational motion of stream in pipe and its transition to the flexural-vortical dynamic structure of translational motion, just as a flexible rod buckling. The introduced criterion allows taking into account an influencing of the inlet geometry, the pipe length, the flow velocity, and also of any physical factors onto stability of the rectilinear flow structure. It is ascertained that the Reynolds number is the number of local hydrodynamic similarity, and it is displayed that one is constituent part of the introduced stability criterion. The developed approach to a problem of stability is applicable for a problem solving on internal flow and external streamline.
PACS: 01.65.+g; 46.32.+x; 47.10.+g; 47.15Fe; 47.27Cn; 47.27Wg; 47.60.+i; 51.20.+d; 83.50.Ha