The long-term changes of ocean surface waves associated with tropical cyclones (TCs) are poorly observed and understood. Here, we present the global trend analysis of TC waves for 1979–2022 based on the ERA5 wave reanalysis. The maximum height and the area of the TC wave footprint in the six h reanalysis have increased globally by about 3%/decade and 6%/decade, respectively. The TC wave energy transferred at the interface from the atmosphere to the ocean has increased globally by about 9%/decade, which is three times larger than that reported for all waves. The global energy changes are mostly driven by the growing area of the wave footprint. Our study shows that the TC-associated wave hazard has increased significantly and these changes are larger than those of the TC maximum wind speed. This suggests that the wave hazard should be a concern in the future.

In the context of global carbon peaking and carbon neutrality goals, the development of clean energy technologies has become a strategic priority for the global community. As a significant source of renewable energy, tidal current energy is playing an increasingly important role in reshaping the global energy landscape. To address the critical scientific challenge presented by the wake effects induced by tidal turbines, this study introduces a high-precision Lagrangian dynamic (LD) sub-grid-scale model within the framework of large-eddy simulation (LES). By integrating the actuator-line model with the aforementioned LD–LES approach, a solver named JUST–FOAM–Turbine is developed, specifically tailored for high-fidelity wake simulations of horizontal-axis tidal turbines (HATTs). The solver's computational accuracy is validated against experimental data obtained from laboratory-scale HATT tests. Subsequently, the solver is employed to analyze the wake dynamics of the HATT under various tip speed ratios (TSRs). The findings are summarized as follows: (1) At low TSRs, the blade operates at a high angle of attack, increasing its susceptibility to stall and flow separation. At high TSRs, the blade experiences a low angle of attack, resulting in a reduced lift coefficient. In contrast, within the optimal TSR range, which corresponds to the blade's primary operational regime, the angle of attack is maintained near the critical value, thereby maximizing the turbine's power output. (2) As the TSR increases, the wake instability of the turbine intensifies, and the wake meandering phenomenon becomes more pronounced. The wake expansion downstream of the turbine is primarily driven by the blockage effect. Further downstream, the wake continues to widen laterally, resulting in an increased expansion width. (3) At a downstream distance of 6D, the wake effect begins to weaken due to momentum exchange between the low-speed region of the wake and the high-speed region of the surrounding water. The radial velocity gradient of the wake decreases significantly. When considering the turbine array layout, it is recommended to position additional turbines downstream beyond 6D. (4) As the TSR increases, the attached vortex on the turbine disk progressively disintegrates, forming small-scale, weaker vortex structures. The third-generation vortex identification method implemented in this study is threshold-independent and effectively captures both strong and weak vortex structures in the turbine wake simultaneously.

A two‐phase fluid flow model solving Navier‐Stokes equations was employed in this paper to investigate liquid sloshing phenomena in cubic tank with horizontal baffle, perforated vertical baffle, and their combinatorial configurations under the harmonic motion excitation. Laboratory experiment of liquid sloshing in cubic tank with perforated vertical baffle was carried out to validate the present numerical model. Fairly good agreements were obtained from the comparisons between the present numerical results and the present experimental data, available numerical data. Liquid sloshing in cubic tank with multiple baffles was investigated numerically in detail under different external excitation frequencies. Power spectrum of the time series of free surface elevation was presented with the aid of fast Fourier transform technique. The dynamic impact pressures acting on the normal and parallel sidewalls were discussed in detail.

The misalignment between flow and rotor can significantly alter the efficiency of the tidal stream turbine (TST), and therefore, it is vital to predict the flow in the tidal field and the performance of the TST under yaw-offset conditions. First, this paper implements a high-precision Lagrangian dynamic sub-grid-scale model based on the large-eddy simulation (LES) method. A classical computational fluid dynamics benchmark case is selected to validate the accuracy of the dynamic LES (DLES) method. The results indicate that the newly implemented dynamic LES method exhibits reduced dissipation and effectively captures the local effects of non-uniform flow fields, including vortex structures. Second, an efficient high-fidelity numerical method (AL-DLES) for forecasting the TST wake is presented by integrating an actuator line (AL) code with the aforementioned DLES method based on the Lagrangian framework. After comparing the experimental results, it was discovered that the newly developed AL-DLES coupling approach, which addresses the issues of challenging turbine meshing, rapid wake dissipation, and insufficient flow field fidelity in previous methods, can accurately simulate the forces acting on the TST while also capturing detailed characteristics of the flow field. Furthermore, the study will be extended to investigate the TST wake dynamics under various yaw-offset conditions, exploring the mechanisms of instability evolution in wake meandering. Meanwhile, the latest third-generation (Ωnew) vortex identification program is implemented and successfully applied to the wake vortex visualization of the TST under yaw-offset conditions. Through a comparative analysis of three distinct vortex identification approaches, it was demonstrated that the Ωnew method exhibits superior accuracy in capturing the vortex system located behind the rotor, eliminating the need for manual threshold selection. In addition, it is capable of simultaneously capturing both strong and weak vortices, which is a vital aspect for future wake research.