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파랑중 선박에 부착된 평판형 부가물에 작용하는 유체력 특성에 관한 기초적 연구
고석원(S.W. Ko),정세민(S.M. Jeong) 한국전산유체공학회 2019 한국전산유체공학회지 Vol.24 No.3
In this study, drag forces acting on a flat plate attached to a vertical wall under harmonic motions in the vertical direction were estimated by numerical simulations to analyze its characteristics, which can be applied for the plate-type appendages of a ship in waves. For the numerical simulations, a commercial CFD software was used with adopting moving domain method to deal with the harmonic motion of the wall with the flat plate. After the benchmark simulations to confirm the accuracy of the present numerical schemes and methods, numerical simulations were performed to estimate the darg coefficients of wall-mounted flat plates under harmonic motion with changing main parameters such as KC(Keulegan-Carpenter) number, aspect ratios, maximum moving velocities and angular frequencies to find the effect and tendency of the parameters on the drag coefficients. From the computational results for the range of KC numbers from 0.7 to 610, it was confirmed that the lower the KC number, the larger the drag coefficient, and the higher the KC number, the tendency of the coefficient to converge to a certain value. As the maximum velocity and period increase, the drag coefficient tends to decrease in the form of a quadratic curve. It was also confirmed that when the dimension of the plate and the KC number are the same, the drag coefficients were identical.
오일러리안 무격자법을 이용한 진동하는 2차원 원주주위 점성 유동 해석
고석원(S.W. Ko),정세민(S.M. Jeong) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.3
In this study, a newly developed Eulerian gridless solver for the simulation of a two-dimensional unsteady incompressible viscous flow around a moving body is introduced. A moving domain method based on the Arbitrary Lagrangian Eulerian(ALE) technique is adopted to implement the moving body. The spatial derivatives of the governing equation are solved by weighted moving least square(WMLS) interpolation over the point cloud. The fractional time step method is adopted and the Poisson equation for pressure is solved successively in the WMLS sense. Simulations of flows around a cylinder moving with constant speed and in harmonic motion are solved for validation and the results are compared with experiments and other CFD simulations. For the constant speed cases, the drag, lift and pressure coefficients estimated by present method were well matched with other results. From the computational results under the harmonic motion with changing main parameters such as Keulegan-Carpenter and Reynolds numbers, the drag and inertial force coefficients using the Fourier series approach were obtained and compared with other results. Even small discrepancy exist, the coefficients were good agreement with other ones.