• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1463-1476
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• 2014

In order to understand hydrodynamic and morphodynamic characteristics under wave-current interactions in an estuary, a coupled model for two-way analysis between existing 3-d numerical wave tank and newly-developed 3-d morphodynamic model has been suggested. Comparing to existing experimental results it is revealed that computed results of the newly-suggested model are in good agreement with each laboratory test result for wave height distribution, vertical flow profile and topographical change around ocean floor pipeline in wave-current coexisting field. Also the numerical result for suspended sediment concentration is verified in comparison with experimental result in solitary wave field. Finally, it is shown that the 3-D coupled Hydro-Morphodynamic model suggested in this study is applicable to morphological change under wave-current interaction in an estuary.

• Journal of the korean society of oceanography
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• v.39 no.1
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• pp.35-45
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• 2004

Based on the MASNUM wave-current coupled model, the temperature and salinity structures along $36^{\circ}N$ in the Yellow Sea are simulated and compared with observations. Both the position and strength of the simulated thermocline are similar to data analysis. The wave-induced mixing is strongest in winter and plays a key role in the formation of the upper mixed layer in spring and summer. Numerical experiments suggest that in the coastal area, wave-induced mixing and tidal mixing control the vertical structure of temperature and salinity.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.1
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• pp.1-8
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• 2001

Wave-induced currents drive nearshore transport processes, and hence an accurate understanding of wave-current interaction is required for proper management of coastal zone. This paper presents details of an adaptive quadtree grid based numerical model of the coupled wave climate and depth-averaged current field. The model accounts for wave breaking, shoaling, refraction, diffraction, wave-current interaction, set-up and set-down, mixing processes, bottom friction effects, and movement of land-water interface at the shoreline. The wave period- and depth-averaged governing equations arc discrctized explicitly by means of an Adarns¬Bashforth second-order finite difference technique on adaptive hierarchical staggered quadtree grids. Results from the numerical model are in reasonable agreement with the laboratory data of longshore current generated by oblique waves on a plane beach (Visser 1980, 1991).

• Coupled systems mechanics
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• v.9 no.5
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• pp.411-432
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• 2020

This research is devoted to the study of plane wave propagation in homogeneous transversely isotropic (HTI) magneto-thermoelastic rotating medium with combined effect of Hall current and two temperature due to multi-dual-phase lag heat transfer. It is analysed that, for 2-D assumed model, three types of coupled longitudinal waves (quasi-longitudinal, quasi-transverse and quasi-thermal) are present. The wave characteristics like phase velocity, specific loss, attenuation coefficients, energy ratios, penetration depths and amplitude ratios of transmitted and reflected waves are computed numerically and illustrated graphically and compared for different theories of thermoelasticity. Some particular cases are also derived from this research.

• Journal of Navigation and Port Research
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• v.36 no.9
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• pp.707-714
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• 2012

Recently, tug boats are widely used for towing a barge which transports building materials, a large block of a ship, offshore crane, and so on. In order to simulate the dynamics of the coupled towing system correctly, the dynamics of the towline should be well modeled. In this paper, the towline was modeled as the multiple finite elements, and each element was assumed as a rigid cylinder which moves in five degrees of freedom except roll. The external tension and its moment acting on each element of the towline were modeled depending on the position vector's direction. Tugboat's motion was simulated in six degrees of freedom where wave and current effects were included, and towed barge was assumed to move in the horizontal plane only. In order to confirm the mathematical models of the coupled towing systems, standard maneuvering trials such as course changing maneuver, turning circle test and zig-zag test were simulated. In addition, the same trials were simulated when the external disturbances like wave and current exist. As the result, it is supposed that the results might be qualitatively reasonable.

• Structural Engineering and Mechanics
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• v.82 no.4
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• pp.491-502
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• 2022

A model experiment with a scale of 1:150 has been conducted to investigate the dynamic responses of a freestanding four-column bridge tower subjected to regular wave, random wave and coupled wave-current actions. The base shear forces of the caisson foundation and the dynamic behaviors of the superstructure were measured and analyzed. The comparisons of the test values with the theoretical values shows that wave-induced base shear forces on the bridge caisson foundation can be approximated by using a wave force calculation method in which the structure is assumed to be fixed and rigid. Although the mean square errors of the base shear forces excited by joint random wave and current actions are approximately equal to those excited by pure random waves, the existence of a forward current increases the forward base shear forces and decreases the backward base shear forces. The tower top displacements excited by wave-currents are similar to those excited by waves, suggesting that a current does not significantly affect the dynamic responses of the superstructure of the bridge tower. The experiment results can be used as a reference for similar engineering design.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1037-1048
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• 2016

In this study, nonlinear wave interaction in the presence of a uniform current is studied using numerical model, named CADMAS-SURF which is based on the Navier-Stokes equations coupled with Volume of Fluid for tracking free surface deformation. The original CADMAS-SURF developed for interaction of wave with structure is modified/extended to simulate nonlinear fluid dynamic motions within wave-current coexisting field. The capability of Numerical Wave-Current Tank (NWCT) in this study is validated by comparing with available existing laboratory experiments for both wave-following and wave-opposing current. The numerical results for interaction between wave and current are shown to be in good agreement with experimental data. Then, this study focused on the dynamic motions of the water velocity, surface elevation and vorticity within combined wave-current field in demonstrating complex nonlinear physical phenomena due to interaction between wave and current. In addition, NWCT is applied to simulate a more complex wave-current-structure field for wave propagating over a submerged breakwater associated with current. Detailed discussion including characteristics of velocity and vorticity fields and the relation between free surface and vorticity are given.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.439-455
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• 2012

Coupled wave induced current modeling system(WIC) was developed from combining with the nearshore spectral wave model, SWAN, the wave induced force model, WIF, and the flow model, EFDC. The reasonable results were obtained from WIC modeling system. The ratio of the wave height calculated with respect to refraction and diffraction effects over submerged spherical shoal was occurred approximately 1~5 % errors compared to Goda(2000)'s result. The radiation stress suggested by Longuet-Higgins and Stewart(1960), the stresses due to rollers in breaking waves proposed by Dally and Osiecki(1994), and Kim(2004)'s new spreading approach instead of the previous lateral mixing approach were added to calculate wave induced force. The results of the WIC modeling system show good agreement with Nishimura et al.(1985)'s laboratory measurements and better than Kim(2004)'s 2 dimensional depth averaged numerical computations for a plane beach with detached breakwater. The present flow field computed agrees reasonably well with the measured flow field. The relative merit of WIF model in WIC modeling system is unconditional stable for time increment.

• Ocean Systems Engineering
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• v.8 no.4
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• pp.381-407
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• 2018

This paper presents a hybrid numerical approach, which combines a two-phase Navier-Stokes model (NS) and the fully nonlinear potential theory (FNPT), for modelling wave-structure interaction. The former governs the computational domain near the structure, where the viscous and turbulent effects are significant, and is solved by OpenFOAM/InterDyMFoam which utilising the finite volume method (FVM) with a Volume of Fluid (VOF) for the phase identification. The latter covers the rest of the domain, where the fluid may be considered as incompressible, inviscid and irrotational, and solved by using the Quasi Arbitrary Lagrangian-Eulerian finite element method (QALE-FEM). These two models are weakly coupled using a zonal (spatially hierarchical) approach. Considering the inconsistence of the solutions at the boundaries between two different sub-domains governed by two fundamentally different models, a relaxation (transitional) zone is introduced, where the velocity, pressure and surface elevations are taken as the weighted summation of the solutions by two models. In order to tackle the challenges associated and maximise the computational efficiency, further developments of the QALE-FEM have been made. These include the derivation of an arbitrary Lagrangian-Eulerian FNPT and application of a robust gradient calculation scheme for estimating the velocity. The present hybrid model is applied to the numerical simulation of a fixed horizontal cylinder subjected to a unidirectional wave with or without following current. The convergence property, the optimisation of the relaxation zone, the accuracy and the computational efficiency are discussed. Although the idea of the weakly coupling using the zonal approach is not new, the present hybrid model is the first one to couple the QALE-FEM with OpenFOAM solver and/or to be applied to numerical simulate the wave-structure interaction with presence of current.

• Journal of Ship and Ocean Technology
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• v.8 no.3
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• pp.26-39
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• 2004

A vessel/mooring/riser coupled dynamic analysis program in time domain is developed for the global motion simulation of a turret-moored, tanker based FPSO designed for 6000-ft water depth. The vessel global motions and mooring tension are simulated for the non-parallel wind-wave-current 100-year hurricane condition in the Gulf of Mexico. The wind and current forces and moments are estimated from the OCIMF empirical data base for the given loading condition. The numerical results are compared with the OTRC(Offshore Technology Research Center: Model Basin for Offshore Platforms in Texas A&M University) 1:60 model-testing results with truncated mooring system. The system's stiffness and line tension as well as natural periods and damping obtained from the OTRC measurement are checked through numerically simulated static-offset and free-decay tests. The global vessel motion simulations in the hurricane condition were conducted by varying lateral and longitudinal hull drag coefficients, different mooring and riser set up, and wind-exposed areas to better understand the sensitivity of the FPSO responses against empirical parameters. It is particularly stressed that the dynamic mooring tension can be greatly underestimated when truncated mooring system is used.