[GTP] IMAGE GTP Seminar October 11, 2010 Chapman Room

[Carolyn Mueller]

Title:  Field Reversals in Rayleigh Benard Convection

Speaker:  Mahendra K. Verma, Physics Department, IIT Kanpur, India

Abstract: In many convection experiments the vertical velocity measured 
near the lateral wall switches sign randomly as a function of time.  
This phenomena has been observed typically for large Rayleigh numbers.  
We present numerical simulations for cylindrical geometry that reproduce 
these reversals.   We observe that the reversals of the large scale 
circulations are induced by its reorientation along the azimuthal 
direction, which is quantified using the phase of the first Fourier mode 
of the vertical velocity measured near the lateral surface in the mid 
plane. Numerically we observe rotation-led and cessation-led 
reorientations, in agreement with earlier experimental results. The 
ratio of the amplitude of the second Fourier mode and the first Fourier 
mode rises sharply during the cessation-led reorientations. This 
observation is consistent with the quadrupolar dominant temperature 
profile observed during the cessations.     

We also present reversals in box geometry, and show that the reversals 
in the box geometry is very similar to those observed for the cylinder.

Mesa Laboratory - Chapman Room
October 11, 2010
3:00 pm

-- 
Carolyn Mueller
NCAR IMAGe
1850 Table Mesa Drive 
Boulder, CO 80305 
www.image.ucar.edu 
Tel: 303 497-2491
Fax: 303-497-2483