NPA Seminar

Seminar on Nonlinear Phenomena and Analysis


   連絡先:手老 篤史(tero(at)

2017年度 現象数理セミナー予定
通常 木曜不定期15:30-17:00・


日時:1月25日(木) 16:00-
場所: C512(九州大学伊都キャンパス・ウエスト1号館)
Helical vortices: theory and applications

Valery L. Okulov
(Department of Wind Energy, Technical University of Denmark)

The main applications of 2D dynamics of helical vortices embedded
in flows with helical symmetry are addressed.
The fundamentals of the 2D helical vortex dynamics lie in
(i) 2D algebraical expression of Biot-Savart law for helical filament;
(ii) analytical solution for self-induced motion of the helical vortex cores;
(iii) Goldstein’s solution for circulation of equilibrium of helical vortex sheets;
(iv) Generalization of Kelvin’s problem on point vortex N-gon stability to helix etc.

The primary assumption of the 2D theory is the hypothesis of helical symmetry
that has been carefully tested in swirling flows in different kinds of swirlers
and vortex generators. Both right- and left-handed helical symmetries were
found in these real flows and hypothesis of existence of possible transitions
between the different types of the vortex structures have been put forward.
The change in axial velocity distribution from a jet-like profile to a wake-like
during vortex breakdown has been investigated from this point of view and
the associated transition from right- to left-handed helical symmetry of the
vorticity field has been confirmed from experimental data and numerical simulations.
Various vortex models for far wakes behind rotors are analyzed.


   連絡先:手老 篤史(tero(at)
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