Colloquium #153 at 4:00 PM on October 12, 2004(Tuesday)
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                            Colloquium #153
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         Institute for Plasma Research, Bhat, Gandhinagar
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                           Dr. Amita Das
                  Institute for Plasma Research,
                     Bhat, Gandhinagar, India.

                                on

                    Intermittency in Turbulence

 Turbulence  is  considered  to  be one of the outstanding physics
 problems. The difficulty in providing a suitable  description  of
 this  particular state stems from the presence of multiplicity of
 scales (infinity) in this particular state. Although  most  prob-
 lems  in  physics  are  associated  with a large number of scales
 and/or degrees of freedom, but in most cases an effective averag-
 ing  over  certain scales and/or considerations of dominance of a
 few specific scales only;  reduces the complexity of the problem.
 There  are,  however,  some areas where the complexity associated
 with the large number of scales manifests in full glory. In  such
 cases   two varieties of approaches viz. (i) statistical and (ii)
 based on the ansatz of scale similarity can be  adopted.  In  the
 context  of turbulence, neither of the two descriptions appear to
 be adequate. The statistical description fails, since  turbulence
 comprises  of  a  complex intermixing of coherence and randomness
 where sporadic bursts of activity  is  punctuated  by  relatively
 quiescent period.  The spatial and temporal bursts of activity in
 this phase is known as intermittent phenomena. Such  intermittent
 activity  is  characterized  by  the deviation of the probability
 distribution function from gaussianity.  The  presence  of  these
 events  are  also  responsible for the failure of second approach
 which is based on the ansatz of scale similarity,  and  has  been
 successfully  applied in the context of phase transition phenome-
 na. I will summarize  the details of recent effort in the  direc-
 tion  of   characterization and developing a proper understanding
 of intermittency in the context of fluid turbulence. In the  con-
 text of plasma turbulence too intermittency studies in  a variety
 of contexts have been carried out, which will be presented in the
 talk. I will also point out at the differences that exist between
 fluid and plasma turbulence, which perhaps warrants a generaliza-
 tion of the notion of intermittency for plasma.



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                       Date:       October 12, 2004 (Tuesday)
                       Venue:      Seminar Hall
                       Programme:  3:40 PM  : Refreshments
                                   4:00 PM  : Talk
                                   5:00 PM  : Discussion
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