An internal wave is a typical dynamic process. As an internal wave, an internal solitary wave usually occurs between two layers of fluids with different densities. Compared with general internal waves, internal solitary waves have large amplitudes, fast propagation speeds, short-wave periods, and often have tremendous energy. The propagation causes strong convergence and divergence of seawater and generates a sudden strong current. Due to its various characteristics, the propagation of internal solitary waves can cause serious harm to offshore engineering structures. Therefore, studying the effects of internal solitary waves on risers is vital in preventing environmental pollution caused by riser damage. Although the research on internal solitary waves has achieved very fruitful results, the research on structures is mostly focused on a single condition, and the occurrence of internal solitary wave, as a complex ocean phenomenon, is often accompanied by many situations. Therefore, this paper constructs a numerical simulation of the interaction between two columns of internal solitary waves and risers. This study explores the force and flow field changes of the riser under the condition of multiple internal solitary waves using the Star-CCM+ software in the simulation. The improved K-epsilon turbulence model was adopted to close the three-dimensional incompressible Navier–Stokes equation, and the solitary wave solution of the eKdV equation was used as the initial and boundary conditions. The interaction between single and double internal solitary waves and a riser was calculated, compared, and analyzed using numerical analysis. The experiment results indicate that the conditions of two internal solitary waves differ from those of a single internal solitary wave. After colliding at the riser, the waves gradually merge into a single wave, and the flow field reaches its minimum velocity. Under the two-wave condition, the horizontal force on the riser as a whole is less than the single-wave condition. As the amplitude difference between the two internal solitary waves gradually decreases, the horizontal opposing force received by the riser first increases and then decreases, while the horizontal positive force gradually decreases.

The Bohai Rim region, one of the prominent coastal economic zones in China, has garnered considerable attention regarding its carbon emission characteristics and driving factors. This paper computes the overall carbon emissions within the Bohai Rim by utilizing economic and energy usage data spanning the years 2009to 2021. The results indicate a clear pattern in carbon emissions, which rise at first before experiencing a decline, primarily driven by substantial contributions from the industrial and transportation sectors. The three-layer extended Log Mean Divisia Index (LMDI) decomposition model examines how different driving characteristics affect carbon emissions, including energy composition, industrial framework, and the level of economic advancement. The study finds that despite regional economic growth, carbon emissions are declining overall. In the industrial sector, emissions reduce in large part by optimizing the energy mix and increasing energy efficiency. Similarly, modal shifts and energy efficiency advancements positively impact emission reduction in the transportation sector. Furthermore, trends in carbon emissions are predicted using a bagging ensemble model for the Bohai Rim region’s two municipalities and three provinces from 2024 to 2060. This study also examines the carbon emission reduction potential under high-speed, low-speed, and normal socio-economic development scenarios. These findings offer an in-depth insight into carbon emissions in the Bohai Rim of China and provide theoretical foundations and policy suggestions aimed at fostering low-carbon growth in related coastal zones.