Observational Study on the Transitional Boundary Layer

Electromagnetic Control of a Transitional Boundary Layer

We investigate numerically the transition to turbulence in a flat-plate boundary layer controlled by electromagnetic forces. The fluid considered is incompressible, Newtonian and low electrically conductive. Similar to boundary layer suction, when applying a steady, wall-parallel, and streamwise oriented Lorentz force, the Blasius velocity profile is transformed to an exponential one. Since the...

Numerical Study On Surface Friction and Boundary Layer Thickening in Transitional Flow

The skin friction on a surface is a major concern by engineers. It is widely accepted that turbulent flow has higher friction than laminar flow due to the higher mixing in boundary layer. However, our new high order DNS found that the high friction is generated in a laminar zone in a transitional flow. Whenever the small length scales are generated, the velocity shear becomes very large in the ...

On the Arctic Boundary Layer On the Arctic Boundary Layer

The boundary layer is the part of the atmosphere that is in direct contact with the ground via turbulent motion. At mid-latitudes the boundary layer is usually one or a few kilometers deep, while in the Arctic it is much more shallow, typically a few hundred meters or less. The reason is that here the absolute temperature increases in the lowest kilometer, making the boundary layer semi-permane...

Surface Friction and Boundary Layer Thickening in Transitional Flow

Boundary layer turbulence in transitional and developed states

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...