Modeling the freestream parameter effect on unsteady boundary layers with positive pressure gradients

The dynamic and thermal parameters of steady and unsteady wall boundary layers are studied on the basis of a two-equation turbulence model under high freestream turbulence intensity and the action of a longitudinal pressure gradient. The freestream parameter effect on the development of dynamic and thermal processes in a steady developed turbulent boundary layer in the flow deceleration zone with a positive pressure gradient is investigated using the modified K-ɛ model. The boundary layer structure is studied and the calculated profiles of the velocity and the kinetic energy of turbulence are compared with the experimental data for the preseparation region. The possibility of the theoretical description of developed turbulent regimes by a quasi-steady turbulence model in the case of periodic temporal dependence of the freestream velocity is shown. An analysis of the calculated parameters of the dynamic and thermal unsteady turbulent boundary layers makes it possible to determine their properties at different oscillation parameters for regions with both zero and positive pressure gradients. The numerical results are compared with experimental data.