Authors & Affiliations
A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia
The paper contains an unconventional description of processes in a moving fluid, oriented to the application of nonstationary flows for numerical calculations using a discrete representation of the flow space and finite time intervals. The formulary of flow mechanics uses two conservation laws - "velocity circulation" and mass and the technology of extrapolating the velocity vector field in a finite time interval. The formulation of the processes clearly contains a feedback between the flow and impenetrable boundaries for the speed rotor. The mechanism of deformation of the velocity field at impermeable boundaries and the appearance of a velocity rotor are shown. Impenetrable boundaries can be considered as part of the current region, inhibited by external forces. The process of removal of the speed rotor from the source at the boundary to the flow is shown. Transport equations for the rotor and speed divergence are given. The mechanism of circulation around internal obstacles and the way of its calculation are considered. The irrotational nature of the velocity field at the beginning of the motion and the history of the development of the flow are shown by the penetration of the vortex into the flow with allowance for the feedbacks. The peculiarities of mixing in nonstationary flows are discussed and it is concluded that it is expedient to consider any problem as nonstationary. This formulation of fluid mechanics makes it possible to simplify numerical approximations in discrete space and time, to reduce the amount of data and to accelerate the solution of nonstationary problems. The formulation of the flow problem was used in the calculation code TURBOFLOW.
numerical simulation, nonstationary flows, discrete time, velocity circulation, impermeable boundaries, vortex generation at the boundary, transport equations, feedback in flow
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