• Title/Summary/Keyword: non-hydrostatic pressure

### A Non-Hydrostatic Pressure Model and its Implementation of the Dynamic Boundary Condition (동수압 모형의 동역학적 경계조건)

• Lee, Jong Wook;Lee, Jin Woo;Cho, Yong-Sik
• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6B
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• pp.691-696
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• 2008
• In this paper, a three-dimensional non-hydrostatic pressure model for free surface flows using a normalized vertical coordinate system is presented. To strongly couple the free surface and non-hydrostatic pressure in the momentum equations, a double predictor-corrector method is employed. This research is especially focused on implementing the dynamic boundary condition (a zero pressure condition) at the free surface. This boundary condition can be specified accurately with a small modification to existing models. Numerical results with and without this modification clearly show that a precise implementation of the dynamic boundary condition is paramountly important.

### Application of a Non-Hydrostatic Pressure Model with Dynamic Boundary Condition to Free Surface Flow (동역학적 경계조건을 갖는 동수압 모형의 자유수면흐름에의 적용)

• Lee, Jin-Woo;Jeong, Woo-Chang;Cho, Yong-Sik
• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.103-109
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• 2010
• In this study, a three-dimensional non-hydrostatic pressure model based on a normalized vertical coordinate system for free surface flows is presented. To strongly couple the free surface and non-hydrostatic pressure with the momentum equations, a double predictor-corrector method is employed. The study is especially focused on implementing the dynamic boundary condition (a zero pressure condition) at the free surface with ignoring of the atmospheric pressure. It is shown that the boundary condition can be specified easily with a slight modification to existing models.

### Effects of Non-hydrostatic Pressure on Free Surface Environmental Flows (자유표면 환경유동에 대한 비정수압 효과)

• Yoon, B.S.;Park, C.W.
• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.116-121
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• 2005
• In the present paper, a new calculation algorithm far solving large scale environmental or geophysical flows with free surface is proposed where the non-hydrostatic pressure component is taken into consideration. Predictor-corrector fractional step approach with explicit, forward time marching scheme in the sigma coordinate system is employed. In order to validate the present calculation algorithm and to estimate the effects of non-hydrostatic pressure on resultant flow and free surface movements, example calculations are carried out for typical steady and unsteady flow problems. Present method can be applied to the meso-scale free surface flows with complex bottom topography where MAC-like 3-d hydrodynamic calculations are quite ineffective and uneconomic.

### Application of Dynamic Boundary Condition to a Non-hydrostatic Pressure Model with Free Surface Boundary (자유수면 경계조건을 갖는 동수압 모형에서의 동역학적 경계조건의 적용)

• Lee, Jin-Woo;Jeong, Woo-Chang;Cho, Yong-Sik
• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.52.1-52.1
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• 2010
• 본 연구에서는 자유수면 흐름을 해석할 수 있는 연직방향에 대해 좌표변환된 3차원 동수압 모형을 제시하였다. 제시한 모형은 자유수면파 동수압의 해석을 위하여, 2중 예측-수정(double predictor-corrector)방법을 적용하였다. 본 연구에서는 자유수면과 동수압을 고려하기 위하여 자유수면 보정단계와 동수압 보정단계로 나누어 정확한 동역학적 경계조건을 적용하는 방법을 제시하였고, 제시한 모형을 이용한 수치모의 결과를 검증하기 위하여 타원형 천퇴에 의한 파의 변형에 대한 수치모의를 실시하였다. 전반적으로 수치모의 결과는 실험자료와 일치하였다.

### Application of the Level Set Method for Free Surface Modeling (자유수면의 모의를 위한 레블셑V 기법의 적용)

• Lee, Hae-Gyun
• The Journal of the Korea Contents Association
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• v.10 no.10
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• pp.451-455
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• 2010
• Hydraulics usually deals with flows with free surface. When the surface curvature is small, the assumption of hydrostatic pressure distribution is enough. However, in the case, when the curvature is big, the non-hydrostatic pressure distribution should be taken into account and the Navier-Stokes equations should be employed instead of the depth-averaged shallow water equations. For the simulation of two immiscible fluids with different characteristics (e.g. water and air, water and oil), the level set method is selected for this purpose. The developed model is applied to classical dam break problem and the computational results are compared with the experimental data. The effectiveness of the developed model is confirmed.

### Characteristics of Water Level and Velocity Changes due to the Propagation of Bore (단파의 전파에 따른 수위 및 유속변화의 특성에 관한 연구)

• Lee, Kwang Ho;Kim, Do Sam;Yeh, Harry
• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5B
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• pp.575-589
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• 2008
• In the present work, we investigate the hydrodynamic behavior of a turbulent bore, such as tsunami bore and tidal bore, generated by the removal of a gate with water impounded on one side. The bore generation system is similar to that used in a general dam-break problem. In order to the numerical simulation of the formation and propagation of a bore, we consider the incompressible flows of two immiscible fluids, liquid and gas, governed by the Navier-Stokes equations. The interface tracking between two fluids is achieved by the volume-of-fluid (VOF) technique and the M-type cubic interpolated propagation (MCIP) scheme is used to solve the Navier-Stokes equations. The MCIP method is a low diffusive and stable scheme and is generally extended the original one-dimensional CIP to higher dimensions, using a fractional step technique. Further, large eddy simulation (LES) closure scheme, a cost-effective approach to turbulence simulation, is used to predict the evolution of quantities associated with turbulence. In order to verify the applicability of the developed numerical model to the bore simulation, laboratory experiments are performed in a wave tank. Comparisons are made between the numerical results by the present model and the experimental data and good agreement is achieved.