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Direct Numerical and Large Eddy Simulations of Transitional Flows around Turbulence Stimulators at Very Low Speeds

초저속 영역에서 난류 촉진기 주위 천이 유동의 직접 수치 및 대형 와 모사

  • Lee, Sang Bong (Department of Naval Architecture and Offshore Engineering, Dong-A University)
  • 이상봉 (동아대학교 조선해양플랜트공학과)
  • Received : 2017.07.20
  • Accepted : 2018.04.18
  • Published : 2018.06.20

Abstract

Direct numerical and large eddy simulations of transitional flows around studs installed on flat plate and bulbous bow have been performed to investigate an effectiveness of turbulence stimulators on laminar-to-turbulence transition at a very low speed. The flow velocity was determined to be 0.366m/s corresponding to 4 knots of full-scale ship speed when the objective ship was Kriso container ship. The spatial evolution of skin friction coefficient disclosed that a fully development of turbulence was observed behind the second stud installed on flat plate while a rapid transition from laminar to turbulence gave rise to the fully development of turbulence behind the first stud installed on bulbous bow. A comparison of streamwise mean velocity profiles showed that the viscous sublayer and log-layer were in good agreement with previous results although the friction velocity of Smagrosinsky sub-grid scale model was about 10% larger than that of direct numerical simulation. While the turbulence intensities of bulbous bow was similar to those of flat plate in inner region, larger intensities of turbulence were observed in outer region of bulbous bow than those of flat plate.

Keywords

References

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