[GTP] Seminar at NCAR- Pablo Mininni

[Silvia Gentile]

INTERPLAY OF ROTATION AND HELICITY IN TURBULENT FLOWS
Pablo Mininni
Turbulence Numerics Team / IMAGe
and
The University of Buenos Aires


Turbulence is ubiquitous in nature, and many turbulent flows are also 
rotating. Mid-latitude synoptic scales in the atmosphere and stellar 
convective regions are examples of such flows. Helicity (alignment of 
the velocity and its curl, the vorticity) is also important for many 
processes in geophysical flows. In the atmosphere, persistence of 
helical flows has been invoked to explain long-lived structures, such as 
those encountered in rotating supercell storms. However, in non-rotating 
isotropic and homogeneous turbulence, even though small-scale structures 
are found to be helical, the helicity of a flow does not seem to alter 
its dynamics. In this talk we consider the effect of helicity in 
rotating flows. With solid body rotation, significant differences emerge 
between helical and non-helical flows. Using high resolution numerical 
simulations, we show that structures differ according to whether 
helicity is present or not, in particular with respect to the emergence 
of Beltrami-core vortices, that are laminar helical long-lived 
structures. Finally, we also discuss how helicity affects the decay of 
structures in rotating turbulent flows.



NCAR

Mesa Laboratory – Main Seminar Room
Tuesday February 22, 2011
10:30am



-- 
Silvia Gentile
NCAR IMAGe
1850 Table Mesa Drive
Boulder, CO 803035
www.image.ucar.edu