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SUMMARY:Multi-scale energy transfers in the near wake of a model wind turb
 ine - Oliver Buxton\, Imperial
DTSTART:20250129T140000Z
DTEND:20250129T150000Z
UID:TALK226381@talks.cam.ac.uk
CONTACT:Anna Walczyk
DESCRIPTION:!https://www3.eng.cam.ac.uk/~pjb1008/talks.cam/buxton.png!\n\n
 A composite image of the instantaneous vorticity (ωz) field in the near w
 ake of a model wind turbine operating at\na tip speed ratio λ = 6 from tw
 o\, non-concurrent\, fields of view. \n\nMany turbulent flows are forced a
 t multiple length scales\, imprinting coherent motions with multiple chara
 cteristic\nfrequencies/length scales simultaneously. Examples include flow
 s through a cityscape or a forest but also past\na wind turbine where cohe
 rent motions are concurrently imparted into the wake by the tower\, nacell
 e\, blade-tip\nvortices etc. In our previous work we developed the multi-s
 cale triple-decomposition of the velocity field into the\nmean\, a sum of 
 various periodic (coherent) motions\, and a stochastic fluctuation [1] \n\
 nu(x\, t) = u(x) + ΣN i=1˜ui(x\, t) + u ′′(x\, t)    (1)\n\nwhich we
  subsequently used to develop the multi-scale triple-decomposed kinetic en
 ergy budgets for the mean flow\,\ncoherent motions\, and stochastic turbul
 ent kinetic energy [2]. The energy budget for the coherent motions contain
 s\na “new” term\, called the triadic production term\, that transfers 
 energy from one coherent mode to another under\nthe catalytic action of a 
 third coherent motion in the triad. This triadic production term was obser
 ved to lead to\nthe formation of secondary modes in simple\, planar multi-
 scale flows [2]. In this talk we will observe the various\ncoherent motion
 s that exist in a wind-turbine wake (reported in [3])\, and how these depe
 nd on the turbine operating\ncondition via the tip speed ratio λ = ΩR/U
 ∞. We will also explore the ways in which the various coherent modes in\
 nthe wake are energised through the framework of the multi-scale triple de
 composed coherent kinetic energy budget\n(reported in [4]). Finally\, we w
 ill examine the influence of free-stream turbulence on both the coherent m
 odes that\nare produced within the wake and the energy transfers that yiel
 d them. \n \n(1)The formatting of the equation does not display correctly.
  "See the PDF version version of this abstract.":https://www3.eng.cam.ac.u
 k/~pjb1008/talks.cam/buxton_abstract.pdf
LOCATION:JDB Seminar RM
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