Boundary layer numerical modeling in a strongly turbulized liquid flow

Already in the first Taylor and Dryden's works it was discovered that besides incoming flow turbulence intensity (measured in percent and defined as the velocity mean squared deviation ratio to the flow averaged velocity), the turbulence influence in an aerodynamic tube is connected with one more parameter, which characterizes the turbulence disturbances size in the flow at large Reynolds numbers (so called turbulence dissipative scale). Turbulence scale is the physical value, characterizing the large eddies size, obtaining its energy from the turbulent flow. Investigation results of the scale and the free-stream turbulence high intensity influence in the boundary layer on a smooth flat plate with a rounded off leading edge (experiment PP169-60) under zero pressure gradient are presented in the study. Using well-known experimental and calculated data the modeling problem of the initially laminar boundary layer transfer to the turbulent one was investigated by numerical methods on the basis of the near-wall modified turbulence model with two additional transfer equations for the turbulent kinetic energy and the turbulence dissipation rate. Turbulent flows modeling near the flat surface with the incoming flow turbulence high level is complicated by two general problems: the definition and description of the laminar-to-turbulent transfer along the surface and the viscous sublayer precise resolution under the developed turbulent mode. While flowing along the flat plate the inviscid liquid with high turbulence degree it is more than 1%, the turbulence scale and the free-stream turbulence intensity joint influence on the flow dynamic and integral characteristics in the boundary layer and turbulence parameters was studied in detail.