Symmetry Breaking, Anomalous Scaling and Large-Scale Flow Generation in a Convection Cell
Abstract
We consider a convection process in a thin loop. At
Ra=R
a
′
cr
a first transition leading to the generation of corner vortices is observed. At higher
Ra
a coherent large-scale flow, which persists for a very long time, sets up. The mean velocity
v
¯
, mass flux $\dm$, and the Nusselt number
Nu
in this flow scale with
Ra
as
v
¯
∝
m
˙
∝R
a
0.45
and
Nu∝R
a
0.9
, respectively. The time evolution of the coherent flow is well described by the Landau amplitude equation within a wide range of
Ra
-variation. The anomalous scaling of the mean velocity, found in this work, resembles the one experimentally observed in the ``hard turbulence'' regime of Benard convection. A possible relation between the two systems is discussed.