Transition to turbulence in strongly heated vertical natural convection boundary layers

Thierry de Larochelambert (1)

1 FEMTO-ST - Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174)

The mechanisms governing the transition to turbulence in natural convection boundary layers along strongly heated vertical walls remain neither very clear nor well understood, because of the lack of experiments and the difficulties of physical modelling. Our measurements bring experimental data focusing on this transition in quiescent air along radiating and conducting plates in the whole range of 2000 to 8000 W/m² heating rate. The analysis of the time series obtained by sliding window cross-correlation thermoanemometry leads us to point out coherent turbulent structures on short heights throughout the thin boundary layer, which seem to be governed by heat transfer and time-microscales of turbulence through the inner sublayer. Physical interpretations are given to relate to the observed heat transfer correlation and these turbulence transition structures along with radiation and conduction.

Mots clés: Natural convection; transition to turbulence; sliding window; cross-correlation; thermoanemometry; microscale; boundary-layer; critical Grashof number

Domaines: Thermique [physics.class-ph]; Thermique [physics.class-ph]

Thierry de Larochelambert. Transition to turbulence in strongly heated vertical natural convection boundary layers. Heat transfer in unsteady and transitional flows, Mar 2003, Eindhoven, Netherlands. pp.183-188. ⟨hal-00347703⟩