Séminaire D2 : The effects of spanwise rotation on wall bounded flows – experiments in rotating plane Couette flow


Nom: 
P. Henrik Alfredsson, Linné Flow Centre, KTH Mechanics, Sweden
Lieu Evenemement: 
SP2MI, bâtiment H2, salle 175/177
Date: 
Miércoles, 16 Enero, 2019 - 14:00
Description: 

System rotation of wall-bounded flows can give large effects on the stability, transition and turbulence due to the action of the Coriolis force. Depending on the rotation direction (cyclonic or anti-cyclonic) a flow (or part of a flow) can be either stabilized or destabilized by the rotation. In the present talk we will discuss various phenomena occurring in spanwise Rotating Plane Couette Flow (RPCF) where experimental results from both flow visualization and stereoscopic PIV will be shown. For fundamental studies RPCF has the advantage as compared to rotating plane Poiseuille flow that the basic mean flow vorticity has the same sign across the channel. For instance, in the anti-cyclonic case streamwise oriented roll cells develop both in the laminar and turbulent cases. Detailed results of these cases will be discussed. We also show that at high enough rotation rates the flow exhibits a state of zero absolute vorticity at the centre of the channel, both in the laminar and turbulent cases. We also show that at some rotation rates the flow at the centre has a larger Reynolds shear stress as compared to the wall shear stress meaning that the mean velocity gradient changes sign in that region.

Departement: 
D2







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