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- Title
Bag-breakup mechanism of sea spray generation in strong winds: direct numerical simulation.
- Authors
Zotova, Anna; Troitskaya, Yuliya; Sergeev, Daniil; Kandaurov, Alexander
- Abstract
In [1] the mechanisms of spray generation under hurricane winds were experimentallystudied and it was found that for friction velocity u* > 1 m/s (for wind speeds at 10 m heightexceeding 20 m/s), bag-breakup determines the contribution to the formation of largedroplets. A typical event of this type begins with a small-scale increase in the water surface,which then turns into a "micro-sail", swells into a water film bounded by a thicker rim, andfinally explodes, producing hundreds of droplets. In the dynamics of engineering fluids [1],this phenomenon is known as the "bag-breakup" mode of liquid fragmentation in gasstreams. For the direct numerical simulation of the bag-breakup phenomenon, the Gerris FlowSolver was used. As an initial configuration for numerical simulation a drop of liquid wasplaced in the air flow. A drop of water with a diameter of 1 cm (the characteristic size of theperturbation from which the bag arises) placed in the air stream at a speed of 20 m/scorresponds best to the experimental situation, such a system is characterized by the Webernumber We = 54. Modeling the dynamics of two media with very different densities, such aswater and air, require a lot of computational time, so we used liquids that differ indensity by a factor of 10, but to keep the same Weber number, we changed theother parameters of the problem. The calculation was carried out with keeping thesame Reynolds number and also with the Reynolds number reduced and increasedby a factor of 10. In our simulation just as in an experiment under the action ofan air stream a drop is blown into a micro-sail that bursts to form a micro-spray.As the Reynolds number decreases (with increasing of viscosity of both media),the process of destruction of the drop after the formation of a micro-sail from itchanges. This work was partly supported by the RFBR grants (18-55-50005, 18-35-20068,19-05-00249). Carrying out experiments themselves was supported by Russian ScienceFoundation (18-77-00074). [1] Troitskaya Yu., et al., Sci. Rep. 7 1614 (2017).
- Subjects
REYNOLDS number; COMPUTER simulation; FRICTION velocity; FLUID dynamics; AIR speed; AIR flow
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article