Faculté des sciences et techniques de l'ingénieur STI, Programme doctoral Mécanique, Institut de génie mécanique IGM (Laboratoire de mécanique des fluides LMF)

Experimental investigation into localized instabilities of mixed Rayleigh-Bénard-Poiseuille convection

Grandjean, Emeric ; Monkewitz, Peter Alexis (Dir.)

Thèse Ecole polytechnique fédérale de Lausanne EPFL : 2008 ; no 4144.

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    Summary
    An experimental study of the stability of the Rayleigh-Bénard-Poiseuille flow was performed in a large transverse aspect ratio channel. The onset for the transverse thermo-convective rolls was determined as a function of the Reynolds number for two different fluids (water: Pr = 6.5 and mineral oil: Pr = 450). Then, the system impulse response was studied and a good agreement with theory was found for the convective/absolute instability transition. Finally the response of the system to localized heating was observed and compared with analytical and numerical results by Martinand, Carrière and Monkewitz (2004 & 2006): experimental thermo-convective global modes are found to correspond to the saturated "steep" variety constructed by Pier, Huerre and Chomaz (2001).