https://www.kriso.re.kr/sciwatch/handle/2021.sw.kriso/65 2026-05-02T14:51:58Z https://www.kriso.re.kr/sciwatch/handle/2021.sw.kriso/508 Title: 고 레이놀즈 수에서의 축대칭 몰수체의 거칠기에 대한 수치연구 Authors: 정태환; 송형도; 염종길; 송성진; 박선호 Abstract: In this paper, the friction drag force of 3D submerged body is investigated by considering the surface roughness, the first grid height, and the Reynolds number using open CFD source code, OpenFOAM 4.0. A procedure for estimating drag components by CFD code is set up and suggested in this study. In the 3D submerged body, because of the form factor in the 3D computations, the friction resistance with the small roughness of 12 ㎛ obtains different result with the smooth wall. As the Reynolds number increased, the boundary layer becomes thinner and the fiction resistance tends to decrease. In the computations for the effect of y+, the friction resistance and wall shear stress are excessively predicted when the y+ value deviates from the log layer. This is presumably because the boundary layer becomes thicker and the turbulence energy is excessively predicted in the nose due to the increase in y+ value. As the roughness increases, the boundary layer becomes thicker and the turbulence kinetic energy on the surface increases. From this study, the drag estimation method, considering the roughness by numerical analysis for ships or offshore structures, can be provided by using the suggested the y+ value and surface roughness with wall function. 2018-01-01T00:00:00Z https://www.kriso.re.kr/sciwatch/handle/2021.sw.kriso/599 Title: 파라미터 변화에 따른 석션버켓기초에 발생하는 세굴현상에 대한 수치해석 연구 Authors: 박선호; 송성진; 왕해청; 정태환; 신윤섭 Abstract: In the case of fixed offshore wind turbines, scouring phenomena have been reported around sub-structures as a result of currents, which seriously damage the structural stability. A parametric study of the various sub-structures of a fixed offshore wind turbine was performed to investigate their effects on the scouring phenomena. For a suction bucket foundation and monopile, the effects of the stick-up heights and water depth were studied, respectively. The open source libraries, called OpenFOAM, were used to simulate a violent flow around a foundation. The numerical methods were selected based on a two-dimensional analysis of a suction bucket. Based on the results for various stick-up heights, a larger scouring region was observed with an increase in the stick-up height because of the down-wash flow around a foundation. Based on the results for various monopile water depths, the water depth had an insignificant effect on the scouring. 2017-01-01T00:00:00Z