Present paper illustrates a new method for solving the two-dimensional turbulent fluid flow for an incompressible fluid near solid walls, using the conservation and momentum equations, in thin layers. The flow separation and reattachment of the fluid at high Reynolds numbers represent the main effect caused by the roughness of surfaces, changes of the domain geometry, and it is encountered in many engineering applications, as the flow in the pipeline systems, turbo-machinery, combustors, or wind turbines. This flow with vortices usually generates vibrations which reduce the efficiency of the hydraulic system. The turbulent boundary layer has a complex structure and characteristics, as the development of vortices, flow separation, etc. and it is not well understood, especially at high Re number. Significant aspects are directly connected with the dependence of the Reynolds number, mainly at high flow velocity, near the solid surfaces. Due to the relative complexity caused by the flow reversal of the adverse or favorable pressure gradient, followed by the streamline curvature, there were imposed different solutions for computation the separated and reattached turbulent flow.  In the present paper is more detailed the capability of different turbulence models to reproduce the flow characteristics of vortices in the forward direction, of the main flow. A practical solution in studying the eddy structure is to improve the statistical model and the sub-grid elements in numerical simulation, especially for those involving a high order of multi-point correlations. Secondly, this solution allows improvement for correlation of the flow aspect at different Reynolds numbers, as a result of external disturbances, and changes of the main flow direction.

The flow equations are solved with a slip velocity using the Navier-Stokes equations, admitting as the first step a pseudo-laminar analysis. The viscous layer is expressed as an integral solution, imposing the wall shear stress as a boundary condition on the solid surfaces. The numerical simulation was performed to investigate the effects of the Reynolds number on flow characteristics near a solid surface, for different models of turbulence, estimating the variation of the turbulent shear stresses. The obtained results were compared with some experimental data, for a large range of Re number. The velocity and shear stress are deduced from the Navier-Stokes equations as long as the convergence is reached, using CFD near the solid surfaces with a strong adverse pressure gradient.  Finally some conclusions and references are mentioned.


Analyzing the Characteristics of Turbulent Vortices at Fast Rolling on Solid Surfaces

Division / Sponsors: 
Heat Transfer Division (HTD), Fluids Engineering Division (FED)

Heat Transfer Summer Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2020/volume/83709

18th International Conference on Nanochannels, Microchannels, and Minichannels
Paper Proceedings: https://asmedigitalcollection.asme.org/ICNMM/ICNMM2020/volume/83693

Fluids Engineering Division Summer Meeting
Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2020/volume/83716

HT-ICNMM2020 - Virtual Conference, SHTC - Virtual Conference, FEDSM2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.