scholarly journals The Vertical Structure of the Surface Wave Radiation Stress for Circulation over a Sloping Bottom as Given by Thickness-Weighted-Mean Theory

2013 ◽  
Vol 43 (1) ◽  
pp. 149-164 ◽  
Author(s):  
Hidenori Aiki ◽  
Richard J. Greatbatch
Keyword(s):  
Delta Function ◽  
Sea Surface ◽  
Wave Radiation ◽  
Radiation Stress ◽  
Weighted Mean ◽  
Mean Velocity ◽  
Pressure Term ◽  
Wave Induced ◽  
Stress Term ◽  
Sloping Bottom

Abstract Previous attempts to derive the depth-dependent expression of the radiation stress have led to a debate concerning (i) the applicability of the Mellor approach to a sloping bottom, (ii) the introduction of the delta function at the mean sea surface in the later papers by Mellor, and (iii) a wave-induced pressure term derived in several recent studies. The authors use an equation system in vertically Lagrangian and horizontally Eulerian (VL) coordinates suitable for a concise treatment of the surface boundary and obtain an expression for the depth-dependent radiation stress that is consistent with the vertically integrated expression given by Longuet–Higgins and Stewart. Concerning (i)–(iii) above, the difficulty of handling a sloping bottom disappears when wave-averaged momentum equations in the VL coordinates are written for the development of (not the Lagrangian mean velocity but) the Eulerian mean velocity. There is also no delta function at the sea surface in the expression for the depth-dependent radiation stress. The connection between the wave-induced pressure term in the recent studies and the depth-dependent radiation stress term is easily shown by rewriting the pressure-based form stress term in the thickness-weighted-mean momentum equations as a velocity-based term that contains the time derivative of the pseudomomentum in the VL framework.

Numerical Study on Coastal Wave and Near-Shore Current Interaction

2014 ◽  
Author(s):  
Jun Tang ◽  
Yongming Shen ◽  
Yigang Lv
Keyword(s):  
Wave Propagation ◽  
Numerical Model ◽  
Water Wave ◽  
Wave Radiation ◽  
Radiation Stress ◽  
Propagation Angle ◽  
Mild Slope Equation ◽  
Near Shore ◽  
Wave Induced ◽  
Wave Radiation Stress

Coastal waves and near-shore currents have been investigated by many researchers. This paper developed a two-dimensional numerical model of near-shore waves and currents to study breaking wave induced current. In the model, near-shore water wave was simulated by a parabolic mild slope equation incorporating current effect and wave energy dissipation due to breaking, and current was simulated by a nonlinear shallow water equation incorporating wave exerted radiation stress. Wave radiation stress was calculated based on complex wave amplitude in the parabolic mild slope equation, and this result in an effective method for calculating wave radiation stress using an intrinsic wave propagation angle that differs from the ones of using explicit wave propagation angle. Wave and current interactions were considered by cycling the wave and current equation to a steady state. The model was used to study waves and wave-induced longshore currents at the Obaköy coastal water which is located at the Mediterranean coast of Turkey. The numerical results for water wave induced longshore current were validated by measured data to demonstrate the efficiency of the numerical model, and water waves and longshore currents were analyzed based on the numerical results.

scholarly journals Derivation of Three-Dimensional Radiation Stress Based on Lagrangian Solutions of Progressive Waves

2017 ◽  
Vol 47 (11) ◽  
pp. 2829-2842 ◽  
Author(s):  
Chao Ji ◽  
Qinghe Zhang ◽  
Yongsheng Wu
Keyword(s):  
Coordinate Transformation ◽  
Atmospheric Pressure ◽  
Three Dimensional ◽  
Sea Surface ◽  
Lagrangian Description ◽  
Radiation Stress ◽  
New Approach ◽  
Progressive Waves ◽  
Analytical Expressions ◽  
Sloping Bottom

AbstractA new approach has been proposed to derive the expressions for three-dimensional radiation stress using solutions of the pressure and velocity distributions and the coordinate transformation function that are derived from a Lagrangian description wherein the pressure is zero (relative to the atmospheric pressure) at the sea surface. Using this approach, analytical expressions of horizontal and vertical depth-dependent radiation stress are derived at a uniform depth and for a sloping bottom, respectively. The results of the depth integration of the expressions agree well with the theory of Longuet-Higgins and Stewart. In the case involving a sloping bottom, the radiation stress expressions from this study provide a better balance of the net momentum compared to those from previous studies.

scholarly journals Numerical Modeling of Wave-Current Flow around Cylinders Using an Enhanced Equilibrium Bhatnagar-Gross-Krook Scheme

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Liming Xing ◽  
Haifei Liu ◽  
Yu Ding ◽  
Wei Huang
Keyword(s):  
Shear Stress ◽  
Lattice Boltzmann ◽  
Current Flow ◽  
Wave Radiation ◽  
Bed Shear Stress ◽  
Force Term ◽  
Radiation Stress ◽  
First Case ◽  
Wave Radiation Stress ◽  
Stress Term

Flow around cylinders is a classic issue of fluid mechanics and it has great significance in engineering fields. In this study, a two-dimensional hydrodynamic lattice Boltzmann numerical model is proposed, coupling wave radiation stress, bed shear stress, and wind shear stress, which is able to simulate wave propagation of flow around cylinders. It is based on shallow water equations and a weight factor is applied for the force term. An enhanced equilibrium Bhatnagar-Gross-Krook (BGK) scheme is developed to treat the wave radiation stress term in collision step. This model is tested and verified by two cases: the first case is the flow around a single circular cylinder, where the flow is driven by current, wave, or both wave and current, respectively, and the second case is the solitary waves moving around cylinders. The results illustrate the correctness of this model, which could be used to analyze the detailed flow pattern around a cylinder.

scholarly journals DRIFT CURRENTS OF CLEAN AND SLICK SEA SURFACES

1982 ◽  
Vol 1 (18) ◽  
pp. 143
Author(s):  
Jin Wu
Keyword(s):  
Surface Film ◽  
Offshore Structures ◽  
Sea Surface ◽  
Clean Surface ◽  
Dynamic Interactions ◽  
Drift Current ◽  
Stress Coefficient ◽  
Wind Velocities ◽  
Wave Induced ◽  
Surface Drift

Drift currents near sea surface govern movement and dispersion of man-made discharges near the sea surface, and influence design, deployment, and stability of offshore structures. The wind-induced drift currents and the wave-induced mass transports at the sea surface are separately estimated. The total surface drift current, the sum of wind- and wave-induced components, agree well with oceanic data (Hughes, 1956). The mass transport of waves over slick surface is greater than that over clean surface due to dynamic interactions between the surface film and waves. On the other hand, the wind-stress coefficient of slick surface is smaller than that of clean surface, resulting in a smaller wind-induced drift current over the slick surface. Available laboratory results (Alofs and Reisbig, 1972) on slick movements are reanalyzed to provide basis for estimating movements of slicks of various sizes over waves of different lengths under different wind velocities.

scholarly journals Effects of Wave–Current Interactions on Suspended-Sediment Dynamics during Strong Wave Events in Jiaozhou Bay, Qingdao, China

2018 ◽  
Vol 48 (5) ◽  
pp. 1053-1078 ◽  
Author(s):  
Guan Dong Gao ◽  
Xiao Hua Wang ◽  
Dehai Song ◽  
Xianwen Bao ◽  
Bao Shu Yin ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Wave Energy ◽  
Jiaozhou Bay ◽  
Sediment Dynamics ◽  
Wave Radiation ◽  
Radiation Stress ◽  
Bottom Stress ◽  
Strong Wave ◽  
Wave Radiation Stress ◽  
Mean Current

AbstractWave–current interactions are crucial to suspended-sediment dynamics, but the roles of the associated physical mechanisms, the depth-dependent wave radiation stress, Stokes drift velocity, vertical transfer of wave-generated pressure transfer to the mean momentum equation (form drag), wave dissipation as a source term in the turbulence kinetic energy equation, and mean current advection and refraction of wave energy, have not yet been fully understood. Therefore, in this study, a computationally fast wave model developed by Mellor et al., a Finite Volume Coastal Ocean Model (FVCOM) hydrodynamics model, and the sediment model developed by the University of New South Wales are two-way coupled to study the effect of each wave–current interaction mechanism on suspended-sediment dynamics near shore during strong wave events in a tidally dominated and semiclosed bay, Jiaozhou Bay, as a case study. Comparison of Geostationary Ocean Color Imager data and model results demonstrates that the inclusion of just the combined wave–current bottom stress in the model, as done in most previous studies, is clearly far from adequate to model accurately the suspended-sediment dynamics. The effect of each mechanism in the wave–current coupled processes is also investigated separately through numerical simulations. It is found that, even though the combined wave–current bottom stress has the largest effect, the combined effect of the other wave–current interactions, mean current advection and refraction of wave energy, wave radiation stress, and form drag (from largest to smallest effect), are comparable. These mechanisms can cause significant variation in the current velocities, vertical mixing, and even the bottom stress, and should obviously be paid more attention when modeling suspended-sediment dynamics during strong wave events.

scholarly journals Changes in Ocean Heat Content Caused by Wave-Induced Mixing in a High-Resolution Ocean Model

2018 ◽  
Vol 48 (5) ◽  
pp. 1139-1150 ◽  
Author(s):  
Lachlan Stoney ◽  
Kevin J. E. Walsh ◽  
Steven Thomas ◽  
Paul Spence ◽  
Alexander V. Babanin
Keyword(s):  
High Resolution ◽  
Ocean Circulation ◽  
Heat Content ◽  
Circulation Model ◽  
Additional Term ◽  
Ocean Model ◽  
Ocean Heat Content ◽  
Sea Surface ◽  
Wave Heights ◽  
Wave Induced

Abstract A parameterization of turbulent mixing from unbroken surface waves is included in a 16-yr simulation within a high-resolution ocean circulation model (MOM5). This “surface wave mixing” (SWM) derives from the wave orbital motion and is parameterized as an additional term in a k-epsilon model. We show that SWM leads to significant changes in sea surface temperatures but smaller changes in ocean heat content, and show the extent to which these changes can reduce pre-existing model biases with respect to observed data. Specifically, SWM leads to a widespread improvement in sea surface temperature in both hemispheres in summer and winter, while for ocean heat content the improvements are less clear. In addition, we show that introducing SWM can lead to an accumulation of wave-induced ocean heat content between years. While it has been well established that secular positive trends exist in global wave heights, we find that such trends are relatively unimportant in driving the accumulation of wave-induced ocean heat content. Rather, in response to the new source of mixing, the simulated ocean climate evolves toward a new equilibrium with greater total ocean heat content.

Free Span Vibrations of Submarine Pipelines in Steady Flows—Effect of Free-Stream Turbulence on Mean Drag Coefficients

1985 ◽  
Vol 107 (4) ◽  
pp. 415-420 ◽  
Author(s):  
A. To̸rum ◽  
N. M. Anand
Keyword(s):  
Free Stream ◽  
Fluid Flows ◽  
Reynolds Numbers ◽  
Steady Flows ◽  
Mean Velocity ◽  
Free Stream Turbulence ◽  
The Mean ◽  
Elastically Supported ◽  
Wave Induced ◽  
Rigid Smooth

In this paper part of the results of a laboratory study related to free span vibrations of submarine pipelines in steady and wave-induced fluid flows are summarized. Tests have been carried out using an elastically supported rigid smooth circular cylinder close to a plane smooth boundary in steady flows with turbulence intensities of 3.4, 5.5, and 9.5 percent for four cylinder gap to diameter ratios, G/D equal to 0.5, 0.75, 1.0, and 3.0. The range of Reynolds numbers based on mean velocity of flow and cylinder diameter was 0.65·104 to 0.35·105. Effect of turbulence intensity on the mean drag force and vibration amplitudes are discussed.

Vertical variation in radiation stress and wave-induced current

2004 ◽  
Vol 51 (4) ◽  
pp. 309-321 ◽  
Author(s):  
Huayong Xia ◽  
Zongwan Xia ◽  
Liangsheng Zhu
Keyword(s):  
Induced Current ◽  
Radiation Stress ◽  
Vertical Variation ◽  
Wave Induced
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