Direct numerical simulation of two turbulent boundary layer flows has been performed. The boundary layers are both subject to a strong adverse pressure gradient. In one case a separation bubble is created while in the other the boundary layer is everywhere attached. The data from the simulations are used to investigate scaling laws near the wall, a crucial concept in turbulence models. Theoreti...

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The mechanics of inhomogeneous turbulence in and adjacent to interfacial layers bounding turbulent and non-turbulent regions are analysed. Different mechanisms are identified according to the straining by the turbulent eddies in relation to the strength of the mean shear adjacent to, or across, the interfacial layer. How the turbulence is initiated and the topology of the region of turbulence a...

Using the recent DNS by Wu and Moin (2010) of a flat-plate boundary layer with a passively heated wall, statistics of the turbulence in transition at Reθ = 500 where spots merge (distributions of the mean velocity, rms velocity and vorticity component fluctuations, kinetic energy production and dissipation rates and enstrophy) have been compared to these statistics for the developed boundary la...

Reynolds-averaged Navier–Stokes (RANS) methods often cannot predict shock/turbulence interaction correctly. This may be because RANS models do not account for the unsteady motion of the shock wave that is inherent in these interactions. Previous work proposed a shock-unsteadiness correction that significantly improves prediction of turbulent kinetic energy amplification across a normal shock in...

Knowledge about the mechanisms of mass transfer across the aqueous boundary layer is still marginal because of the lack of suitable experimental techniques. We present a new technique to measure the air-water gas transfer rate and the spatial structure of the micro turbulence at the ocean surface using passive thermography. We make use of the fact that due to radiative cooling, latent and sensi...

An energy-spectrum bottleneck, a bump in the turbulence spectrum between the inertial and dissipation ranges, is shown to occur in the nonturbulent, one-dimensional, hyperviscous Burgers equation and found to be the Fourier-space signature of oscillations in the real-space velocity, which are explained by boundary-layer-expansion techniques. Pseudospectral simulations are used to show that such...

The unique atmospheric conditions present at sites such as Dome C on the Antarctic plateau are very favorable for high spatial resolution astronomy. At Dome C, the majority of the optical turbulence is confined to a 30 to 40 m thick stable boundary layer that results from the strong temperature inversion created by the heat exchange between the air and the ice-covered ground. To fully realize t...

In the present work are presented results from numerical simulations performed with the ANSYS-CFX code. It is studied a radial diffuser flow case, which is the main academic problem used to study the flow behavior on flat plate valves. The radial flow inside the diffuser has important behaviors such as the turbulence decay downstream and recirculation regions inside the valve flow channel due t...