• Development of a turbulent boundary layer.
  
  • Introduction: boundary layer and acceleration
    The turbulent movement of a viscous fluid near a solid surface is a transition between the external flow (far from the surface) and the null velocity condition at the surface.
    
    (Original Image courtesy of Symscape)
    In the case of a flow where the thickness of this transition is small respect to the total flow height, the presence of the solid has a little impact on the external flow velocity. On the other hand, in the cases of confined flows inside flume or pipes, the flow may become overdrawn because the boundary layer reduces the flow in such a way that the external flow must accelerate to preserve the mass balance. This is called acceleration due to the boundary layer.
  
  
  • Velocimetry in flume
    The HERODE flume characteristics needed to be qualified. To this end, I performed hot-wire, PIV (particle image velocimetry) and LDV (laser doppler velocimetry) measurements at different location in the flume. By this way the shear stress of the flow could have been measured in function of the water height and the water flow (for erosion measurements).
  
  
  • On the generalization of acceleration laws
    At comparing our results with those of the literature, it has been noticed that the phenomenological laws did not agree. We undertook an investigation that lead to a self-similar parameter that was gathering well all the results. Elsewhere, these results have all been confirmed by some numerical simulations and still need to be validated and published.
  
  
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© 2009 Fabien Ternat