Research areas and strategies

Research areas and strategies

At the current stage FLOW has six different priority research areas which are:

The overall FLOW strategy may be downloaded here.

Stability and transition

The area of Stability and transition deals with how and why orderly laminar fluid transitions to chaotic turbulent flow. Research will be concentrated on receptivity, stability of flows in complex geometries and classical stability problems. The responsible person for the Stability and transition research area is Jens Fransson and the research strategy may be downloaded here.

Figure: Wind tunnel smoke visualization of transition in a boundary layer subjected to free stream turbulence carried out at KTH. The figure shows the development of streamwise streaks, secondary instabilities and the breakdown to a turbulent spot. The flow is from left to right.

Flow control and optimization

The area of Flow control and optimization takes a step further from analyzing and understanding flows and deals with how flows can be manipulated and optimized in order to achieve the objectives at hand. Research will be concentrated on feedback control, laminar flow control and separation control. The responsible person for the Flow control and optimization research area is Luca Brandt and the research strategy may be downloaded here.

Figure: A snapshot showing complex vortical structures in a canonical turbulent boundary layer

High Reynolds-number turbulence, incl. geophysical flows

High-Reynolds-number turbulence is the archetype of highly nonlinear chaotic systems possessing many degrees of freedom and a wide span of scales and geophysical flows deals with the flows in the atmosphere and oceans. The responsible person for the High Reynolds-number turbulence including geophysical flows research area is Arne Johansson and the research strategy may be downloaded here.

 

Figure: Potential vorticity snapshot from a freely decaying quasi-geostrophic simulation. Red (blue) colour corresponds to positive (negative) potential vorticity.

 

 

Micro- and complex fluids

Micro-fluidics deals with research on the special problems that appear when flow systems are built in micron sizes or less whereas complex fluids usually refers to fluids with more challenging properties than single phase flows of air and water, such as polymeric solutions, foams and emulsions. The responsible person for the Micro- and complex fluids research area is Anna-Karin Tornberg and the research strategy may be downloaded here.

Figure: Simulation of sedimenting rigid fibers. The configuration is shown initially and at two later times. The clustering of fibers and their increased vertical alignment can be seen to increase their sedimentation speed, as indicated in the plot to the right of each box.

Low Mach-number aeroacoustics

Aero-acoustics is the part of fluid mechanics where the generation and propagation of sound in a moving media are studied. Within the area of Low Mach-number aero-acoustics research will be concentrated on interior flows where new and improved experimental and numerical methods will be developed for characterizing aero-acoustic sources. The use of flow control on aero-acoustic sources and dissipation of acoustic energy will also be studied. The responsible person for the Low Ma-number aeroacousticsresearch area is Gunilla Efraimsson and the research strategy may be downloaded here.

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Figure: Contours of the mean velocity (top), instantaneous velocity (middle) and instantaneous density (bottom) for a flow through an orifice.

 

e-Science in fluid mechanics

The e-science in fluid mechanics research area has a different character compared to other research areas in FLOW. It is not focused on a single discipline of fluid mechanics but its activities span over all other research areas in FLOW. It also acts as a link to the Swedish e-Science Research Centre (SeRC) since it represents the FLOW community in that centre. The responsible person for the e-Science in fluid mechanics research area is Philipp Schlatter and the research strategy may be downloaded here.

 

Figure: Visualisation of the vortical structures in a jet in crossflow, showing the appearance of hairpin vortices downstream of the nozzle.

 

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