Turbulent boundary layers; dynamic and irregular interfaces

Turbulence occours at all kinds of interfaces, those which separate a fluid and a solid and those between fluids with different flow properties or compositions, most notably density. This is called boundary layers, and are common in diverse physical systems, from the atmosphere to the ocean and in pipe flows. The intention of this project is to examine aspects of a coupled interface system.

Figure: Lattice Boltzmann model of fluid flow in a rough channel at Reynolds number 10,000 using 50 million grid points. Color scale illustrates vorticity. Eddies nucleate at the rough fluid-solid Interface.

Figure: Lattice Boltzmann model of fluid flow in a rough channel at Reynolds number 10,000 using 50 million grid points. Color scale illustrates vorticity. Eddies nucleate at the rough fluid-solid Interface.

About the research

Turbulence is ubiquitous at interfaces, those which separate a fluid and a solid and those between fluids with different flow properties or compositions, most notably density. In such boundary layers, turbulence mediates the transfer of heat and momentum between the adjoining fluids/solids. Such layers are common in diverse physical systems, from the atmosphere to the ocean and in pipe flows.

Two applications are of particular interest. One concerns the layers occurring at the reactive, rough walls of pipes or conduits. The deposition/corrosion processes localized at the pipe’s walls generate rough boundaries that change the flow properties in the pipe. Complex flow patterns and transport behavior, such as ultimate clogging, results from the fluid-solid interaction. This is relevant to many-man made systems, pipelines industry, and is encountered in many geological systems.

The second application concerns the air-sea interface. In contrast to the previous examples, this represents the boundary between a fluid and a gas; but similar phenomena are at play. The air-sea interface  is comprised of two turbulent boundary layers, one at the ocean surface and the other at the base of the atmosphere. The interface moreover is highly dynamic. Surface waves, for example, frequently break, enhancing turbulent exchange. The heat transferred across this interface has a direct effect on the  winds in the atmosphere and can even impact the position of the storm tracks. The atmospheric and oceanic boundary layers are usually studied separately, but nevertheless exhibit common properties. Our intention is to examine aspects of the coupled interface system, in the laboratory and numerically.

Cooperation

Published Nov. 5, 2015 12:12 PM - Last modified Dec. 11, 2015 2:38 PM