Authors & Affiliations
Shcherbakov S.I.
A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia
Shcherbakov S.I. – Senior Researcher. Contacts: 1, Bondarenko pl., Obninsk, Kaluga region, Russia, 249033. Tel.: (484) 399-84-43; e-mail:
Abstract
The work is devoted to the description of the interaction in a turbulent flow (transfer of momentum), calculated through the space-averaged characteristics of the flow, for use in numerical calculations in the discrete region. A computational model is proposed that, in addition to the traditional description of the interaction through shear stresses and turbulent viscosity, contains a new mechanism of local drags proportional to the local shear rate of the fluid and the velocity of the fluid itself. There are two reasons why the proposed model was implemented. The first is a theoretical description of the mechanisms of turbulence in a flowing fluid. There were two mechanisms: self-generation of local short-term decelerations of the flow and the formation of many small toroidal vortices as a result of instability during the stretching of vortex tubes. The dual structure of interaction forces in a turbulent flow must be implemented in computational models. The second reason is that it is almost impossible to obtain acceptable results in the calculation of complex geometries with one set of constants for the model of shear stresses – the equivalent viscosity should change tenfold over the flow space, which is doubtful. The proposed algebraic model of turbulent interaction contains an additional description of normal turbulent stresses caused by local decelerations in the flow and leading to a redistribution of velocities in the flow section. Taken together, the model has two constants and makes it possible to obtain reliable results in cases where knowledge of the location and size of flow structures in the equipment space is important without an accurate analysis of the velocity profile. The model is used in the Turboflow computational environment for comparative analysis of engineering solutions.
Keywords
turbulent fluid flow, numerical calculation, averaged velocities, large computational grid, algebraic turbulence models
Article Text (PDF, in Russian)
UDC 532.517.4