DNS of a turbulent boundary layer using inflow conditions derived from 4D-PTV data

Unsteady, 3D particle tracking velocimetry (PTV) data are applied as an inlet boundary condition in a direct numerical simulation (DNS). The considered flow case is a zero pressure gradient (ZPG) turbulent boundary layer (TBL) flow over a flat plate. The study investigates the agreement between the experimentally measured flow field and its simulated counterpart with a hybrid 3D inlet region. The DNS field inherits a diminishing contribution from the experimental field within the 3D inlet region, after which it is free to spatially evolve. Since the measurement does not necessarily provide a spectrally complete description of the turbulent field, the spectral recovery of the flow field is analyzed as the TBL evolves. The study summarizes the pre-processing methodology used to bring the experimental data into a form usable by the DNS as well as the numerical method used for simulation. Spectral and mean flow analysis of the DNS results show that turbulent structures with a characteristic length on the order of one average tracer particle nearest neighbor radius (r) over bar (NN) or greater are well reproduced and stay correlated to the experimental field downstream of the hybrid inlet. For turbulent scales smaller than (r) over bar (NN), where experimental data are sparse, a relatively quick redevelopment of previously unresolved turbulent energy is seen. The results of the study indicate applicability of the approach to future DNS studies in which specific upstream or far field boundary conditions (BCs) are required and may provide the utility of decreasing high initialization costs associated with conventional inlet BCs.

Automated summary

The study applies unsteady 3D particle tracking velocimetry (PTV) data as an inlet boundary condition in direct numerical simulation (DNS) for a zero pressure gradient (ZPG) turbulent boundary layer (TBL) flow over a flat plate. The agreement between experimental flow field and simulated counterpart with a hybrid 3D inlet region is investigated. Results show that turbulent structures with a characteristic length on the order of one average tracer particle nearest neighbor radius or greater are well reproduced downstream of the hybrid inlet, while smaller turbulent scales can quickly redevelop previously unresolved turbulent energy.