Journal of Marine Science and Engineering

Ice accretion on arctic vessels and offshore platforms poses serious threats to navigation and operational safety. Existing research has primarily focused on isolated structures. This study employs a combined approach of numerical simulation and experimental validation. It systematically investigates the icing characteristics of tandem twin-cylinders in wake flow fields. This configuration is common yet rarely studied in real marine environments. The model employs two identical cylinders arranged in tandem. It examines the effects of wind speed, distance, diameter, and wind direction angle on ice accretion morphology and distribution. Validation was conducted through wind tunnel tests at 5 m/s wind speed and 2.0 g/m³ liquid water content. Results demonstrate a significant shielding effect from the upstream cylinder wake. As wind speed increases, the ice mass difference between upstream and downstream cylinders widens. Ice mass shows a nonlinear relationship with distance. Minimum ice accretion on the downstream cylinder occurs at 350–450 mm distance. This results from wake pattern transition. The shielding effect exhibits strong nonlinear dependence on wind direction angle. A deviation of 8.2° increases total ice mass by 242.5%. Multivariable analysis confirms these nonlinear mechanisms persist under coupled distance–wind speed variations. This study provides the first systematic revelation of twin-cylinder icing mechanisms in wake flow fields. It offers a validated predictive tool for anti-icing design of arctic marine structures.

The first oil and gas well in the South Yellow Sea Basin was completed in 1961. In 1984, 2.45 tons of light oil were obtained from the Cenozoic strata. However, it remains the only large oil and gas basin in China’s offshore area without industrial oil and gas discoveries. Although the consensus is that the South Yellow Sea Basin is a foreland basin, and the oil and gas exploration prospects are promising, the research on the regional structure and the tectonic evolution of the foreland basin system is weak, which seriously hinders the process of industrial oil and gas discoveries. This paper reports the results of over 30 years of onshore and offshore investigations and well-seismic joint interpretation in the study area: for the first time, the mountains and basins formed by the collision of the North China and Yangtze plates were discovered in the geological survey of the northern islands of the South Yellow Sea Basin; the C-type eclogite chronology of Qianliyan Island, the characteristics of the foreland basins and intracontinental foreland basins around the South Yellow Sea, and the tectonic evolution characteristics and models of the basins were clarified. Through the zircon/phosphate fission track analysis of the deep black Jurassic strata in the Qianyuan S-2 well, it was revealed that the collision and subduction of the Pacific Plate against the Eurasian Plate since the Late Cretaceous–Paleogene led to large-scale uplift movements, and more than 3000 m of strata were eroded in the basin area. This is consistent with the multiple unconformities of E/N, K/N, and T₂/N identified by well-seismic joint interpretation, and is also the main reason why oil and gas have been difficult to preserve in the South Yellow Sea Basin since the Middle Triassic–Jurassic. Deep prototype oil and gas exploration in the basin may be the preferred option for current oil and gas exploration deployment, which is conducive to achieving industrial oil and gas discoveries.

Rivers discharge a substantial amount of nutrients into the bay, which constitutes a key area of research in water pollution and environmental management. However, research on the influence of river input on various nitrogen components in semi-enclosed bays like the Zhanjiang Bay remains limited. This study conducted on-site monitoring and cultivation experiments in Zhanjiang Bay. Consequently, a systematic investigation was conducted on the influence of river inputs on the migration and change in different nitrogen components, primarily dissolved inorganic nitrogen (DIN). The results showed that the DIN flux during the rainy season was the greatest input flux, amounting to 9724 t, which accounted for 45.6% of the annual DIN flux. The fluxes of NO₂-N and NO₃-N were the highest during the rainy season, accounting for 49% and 52% of the total annual flux, respectively. Based on on-site cultivation under different salinity conditions (5, 15, and 25), the DIN content decreased much faster in lower-salinity waters, with the highest average daily change rate of −16.3 μmol/dm³ in a salinity of 5. This indicated that hydrodynamic mixing and exchange processes have a significant impact on the variations in inorganic nitrogen components. Therefore, the results of this study provide valuable insights into the migration and change in inorganic nitrogen components in estuarine water bodies. It also holds significance for guiding the treatment of environmental pollution in estuaries, such as addressing the sewage discharge from the steel industry.