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Flow control is one of the hottest research areas in fluid mechanics. It is probably the most efficient way to meet demands for competitive and efficient solutions for the industry.

"The process or operation by which certain characteristics of a given flow are manipulated in such a way as to achieve improvements of a specific technical performance." (Fiedler 1998). This definition gives a good description of the research field of flow control. The birth of this field scientifically goes back to 1904 when Prandtl presented his work On Fluid Motion with Very Small Friction at the Third International Congress of Mathematicians held at Heidelberg, Germany. The boundary-layer theory was introduced and controlled actively by steady suction in order to delay separation on a surface of a cylinder. The advancement of flow control since then has been rather slow. However, today, the use of active flow control (AFC) is gaining momentum. Examples of the use of AFC are
  • drag reduction for bluff bodies (vehicles, aeroplanes, ships)
     
  • lift enhancement (or reduction) for aeroplanes and helicopters
     
  • separation control in internal flow to reduce pressure drop and/or increasing the functionality of the device
     
  • noise control
     
  • transition control: preventing a laminar boundary layer to transition to a turbulent one
     
Large eddy simulation is an efficient tool for designing efficient use of AFC.
 
 
 
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"The process or operation by which certain characteristics of a given flow are manipulated in such a way as to achieve improvements of a specific technical performance."
(Fiedler 1998).
Page by I Ljungström