Journal of the Society of Naval Architects of Korea (대한조선학회논문집)

The Society of Naval Architects of Korea (대한조선학회)
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Computation of Turbulent Flow around a Ship Model with Free-Surface

자유표면을 포함한 선체주위 난류유동 해석

  • 김정중 (삼성중공업 조선플랜트연구소) ;
  • 김형태 (충남대학교 선박해양공학과)
  • Published : 2001.02.01
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Abstract

The computations of the turbulent flow around the ship models with the free-surface effects were carried out. Incompressible Reynolds-Averaged Navier-Stokes equations were solved by using an explicit finite-difference method with the nonstaggered grid system. The method employed second-order finite differences for the spatial discretization and a four-stage Runge-Kutta scheme for the temporal integration. For the turbulence closure, a modified Baldwin-Lomax model was exploited. The location of the free surface was determined by solving the equation of the kinematic free-surface condition using the Lax-Wendroff scheme and a free-surface conforming grid was generated at each time step so that one of the grid boundary surfaces always coincides with the free surface. An inviscid approximation of the dynamic free-surface boundary condition was applied as the boundary conditions for the velocity and pressure on the free surface. To validate the computational method developed in the present study, the computations were carried out for beth Wigley and Series 60 $C_B=0.6$ ship model and the computational results showed good agreements with the experimental data.

본 논문에서는 비압축성 Reynolds-Averaged Navier-Stokes 방정식을 수치 해석하여 자유표면을 포함한 선체 주위의 난류 유동을 계산하였다. 정규격자 상에서 공간의 이산화는 2차 정도의 유한차분법을, 시간의 적분에는 4단계 Runge-Kutta법을 이용하였고, 난류 닫힘 조건을 만족시키기 위해 Baldwin-Lomax 난류 모형을 사용하였다. 자유표면의 위치는 운동학적 경계조건식을 Lax-Wendroff법으로 풀어서 구하였고, 자유표면과 격자 경계면을 일치시키기 위해 매 시간마다 새로 계산된 자유표면 위치에 맞추어 격자를 새로 구성하였다. 속도와 압력에 대한 경계조건은 자유표면에서 점성을 무시하여 근사한 동역학적 조건을 적용해서 구하였다. 본 연구에서 개발된 수치해법을 검증하기 위하여 실험자료가 많은 Wigley 선형과 Sries 60 $C_B=0.6$ 선형에 대해 수치계산을 수행하였고 계산된 선체 주위의 파형이 실험 결과와 잘 일치하는 것을 확인하였다.

Keywords

References

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