scholarly journals Tuning of vessel parameters including sea state dependent roll damping

2021 ◽  
Vol 233 ◽  
pp. 109084
Author(s):  
Xu Han ◽  
Svein Sævik ◽  
Bernt Johan Leira
Keyword(s):  
Sea State ◽  
Roll Damping ◽  
State Dependent

scholarly journals Impact of Sea-State-Dependent Langmuir Turbulence on the Ocean Response to a Tropical Cyclone

2016 ◽  
Vol 144 (12) ◽  
pp. 4569-4590 ◽  
Author(s):  
Brandon G. Reichl ◽  
Isaac Ginis ◽  
Tetsu Hara ◽  
Biju Thomas ◽  
Tobias Kukulka ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Three Dimensional ◽  
Ocean Model ◽  
Stokes Drift ◽  
Langmuir Turbulence ◽  
Sea State ◽  
Near Surface ◽  
Ocean Response ◽  
State Dependent ◽  
The Impact

Abstract Tropical cyclones are fueled by the air–sea heat flux, which is reduced when the ocean surface cools due to mixed layer deepening and upwelling. Wave-driven Langmuir turbulence can significantly modify these processes. This study investigates the impact of sea-state-dependent Langmuir turbulence on the three-dimensional ocean response to a tropical cyclone in coupled wave–ocean simulations. The Stokes drift is computed from the simulated wave spectrum using the WAVEWATCH III wave model and passed to the three-dimensional Princeton Ocean Model. The Langmuir turbulence impact is included in the vertical mixing of the ocean model by adding the Stokes drift to the shear of the vertical mean current and by including Langmuir turbulence enhancements to the K-profile parameterization (KPP) scheme. Results are assessed by comparing simulations with explicit (sea-state dependent) and implicit (independent of sea state) Langmuir turbulence parameterizations, as well as with turbulence driven by shear alone. The results demonstrate that the sea-state-dependent Langmuir turbulence parameterization significantly modifies the three-dimensional ocean response to a tropical cyclone. This is due to the reduction of upwelling and horizontal advection where the near-surface currents are reduced by Langmuir turbulence. The implicit scheme not only misses the impact of sea-state dependence on the surface cooling, but it also misrepresents the impact of the Langmuir turbulence on the Eulerian advection. This suggests that explicitly resolving the sea-state-dependent Langmuir turbulence will lead to increased accuracy in predicting the ocean response in coupled tropical cyclone–ocean models.

A Sea State–Dependent Spume Generation Function

2009 ◽  
Vol 39 (9) ◽  
pp. 2363-2372 ◽  
Author(s):  
James A. Mueller ◽  
Fabrice Veron
Keyword(s):  
Wind Forcing ◽  
Limited Data ◽  
Sea State ◽  
Generation Function ◽  
Scalar Fluxes ◽  
Droplet Distribution ◽  
State Dependent ◽  
Constant Form ◽  
New Generation ◽  
Good Agreement

Abstract The uncertainty of the sea spray generation function continues to obscure spray-mediated momentum and scalar fluxes, especially for intense wind conditions. Most previous studies assume a constant form (spectral shape) for the droplet distribution, even though a shift to smaller drops with increased wind forcing is expected. In this paper, a new generation function for spume drops is derived, but unlike previous studies, both its form and magnitude change with wind forcing. Fairly good agreement is found between this spume generation function and the limited data available. A potential explanation for the vast size differences among previous spume generation studies is also provided by distinguishing the drops formed at the surface from the drops transported vertically where measurements are routinely made.

scholarly journals The Effects of Sea Spray and Atmosphere–Wave Coupling on Air–Sea Exchange during Tropical Cyclone

2017 ◽  
Author(s):  
Nikhil Garg ◽  
Yin Kwee Eddie Ng ◽  
Srikanth Narasimalu
Keyword(s):  
Tropical Cyclone ◽  
Numerical Simulations ◽  
Surface Waves ◽  
Momentum Flux ◽  
Ocean Surface ◽  
Heat Fluxes ◽  
Sea Spray ◽  
Sea State ◽  
Ocean Surface Waves ◽  
State Dependent

Abstract. The study investigates the role of air–sea interface using numerical simulations of an Atlantic Hurricane Arthur (2014). More specifically, present study aims to discern the role ocean surface waves and sea spray play in modulating the intensity and structure of a tropical cyclone (TC). To investigate the effects of ocean surface waves and sea spray, numerical simulations were carried out using a coupled atmosphere–wave model where a sea spray microphysical model was incorporated within the coupled model. Furthermore, this study also explores how sea spray generation can be modelled using wave energy dissipation due to whitecaps, where whitecaps are considered as the primary mode of spray droplets generation at hurricane intensity wind speeds. Three different numerical simulations including sea state dependent momentum flux, sea spray mediated heat flux and combination of former two processes with sea spray mediated momentum flux were conducted. The foregoing numerical simulations were evaluated against the National Data Buoy Center (NDBC) buoy and satellite altimeter measurements as well as a control simulation using an uncoupled atmosphere model. The results indicate that the model simulations were able to capture the storm track and intensity, where the surface wave coupling results in a stronger TC. Moreover, it is also noted that when only spray mediated heat fluxes are applied in conjunction with sea state dependent momentum flux, they result in a slightly weaker TC, albeit stronger compared to the control simulation. However, when spray mediated momentum flux is applied together with spray heat fluxes, it results in a comparably stronger TC. The results presented here alludes to the role surface friction plays in intensification of a TC.

scholarly journals Sea-state-dependent wind work on the oceanic general circulation

2013 ◽  
Vol 40 (12) ◽  
pp. 3150-3156 ◽  
Author(s):  
Guoqiang Liu ◽  
William Perrie
Keyword(s):  
General Circulation ◽  
Sea State ◽  
State Dependent

Springing Analysis of Elastic Vessels in Head and Oblique Seas Including Nonlinear Effects Due to Second Order Diffraction Pressures

2004 ◽  
Author(s):  
Haiping He ◽  
Armin W. Troesch ◽  
Yung Sup Shin ◽  
Boo-Ki Kim
Keyword(s):  
Theoretical Calculations ◽  
Bending Moment ◽  
Nonlinear Effects ◽  
Diffraction Theory ◽  
Ocean Waves ◽  
Second Order ◽  
Sea State ◽  
Zero Crossing ◽  
Sum Frequency ◽  
State Dependent

The wave-induced vibration of the ship hull, commonly called springing, may not produce extreme stresses, but it is likely to have a direct effect on fatigue-life estimates due to its high frequency content. This research investigates the second order contribution to the springing bending moment from the sum frequency of incident ocean waves in both head and oblique seas. The computer program developed here extends the ABS SSRS (Ship Spring Response System) program to oblique seas using Troesch’s oblique sea linear diffraction theory [1]. The theoretical calculations for forward speed are modified by an empirical factor to correlate more closely with experimental results. An example calculation on a Bulk Carrier was performed for different heading angles. For one such representative sea state, the overall increase to the total bending moment from the nonlinear, sum-frequency excitation is found to be less than 12%. However, the nonlinear springing (RMS) increases the total RMS springing over the linear springing by more than 5 times in some stations, which has significant implications for fatigue studies. A sea state sweep study (using ITTC spectrum) also shows the springing effects are highly sea state dependent. Overall, springing effects decrease as zero crossing periods increase, which indicates springing is important in sea states with short waves and becomes less significant in sea states with long waves.

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