F. T. M. Nieuwstadt

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Results are presented from a large eddy simulation (LES) and wind tunnel study of the turbulence regime in a horizontally evolving sheared atmospheric convective boundary layer (CBL) capped by a temperature inversion. The wind tunnel part of the study has been conducted in the thermally stratified tunnel of the University of Karlsruhe. For the numerical(More)
Modifications of turbulence regime in the sheared convective boundary layer (CBL) by a number of external nonbuoyant forcings are studied experimentally in a thermally stratified wind tunnel and numerically by means of large eddy simulation. This type of CBL is observed in the atmosphere when an originally neutral or stable air mass is advected over a(More)
Transition to turbulence in pipe flow is one of the most fundamental and longest-standing problems in fluid dynamics. Stability theory suggests that the flow remains laminar for all flow rates, but in practice pipe flow becomes turbulent even at moderate speeds. This transition drastically affects the transport efficiency of mass, momentum, and heat. On the(More)
Control theory is used to determine optimal disturbances in pipe flow and the forcing, in the form of blowing and suction at the wall, capable of attenuating them. An approach is adopted, based on a parabolic approximation of the linear Navier–Stokes equations, which is appropriate when dealing with asymptotically elongated (in the streamwise direction)(More)
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