Jie-Min Zhan

A proportion of 0.69% of the Earth’s land surface had been urbanized. Urbanization had led to changes in the physical properties and biological characteristics of the Earth’s surface, which changed the regional and global climate subsequently. The impact of urbanization on temperature, wind speed, and relative humidity in an extreme heat process in Guangdong Province, China, had been investigated in this paper. The CMA‐TRAMS (the Tropical Regional Atmosphere Model System of South China of the China Meteorological Administration) model was used with different land cover data. The results indicated that the change of land cover had relatively more effects on characteristics (temperature, wind speed, and humidity) in daytime, represented by results at 14:00, compared to that at 02:00. The combination of increased temperature, decreased wind speed and humidity as a result of urbanization could increase the heat storage in daytime. Urbanization could cause significant impact on temperature, which in turn affected the wind speed and the relative humidity. The findings provided valuable insights into studying high‐temperature events in the region and offered predictions regarding the future influence of urbanization on climate.

This study investigates the effects of filing angles at the slits of a curtain coater on the formation, stability, and thickness uniformity of integrated lacquer curtains. Using a novel micro-scale measurement technique, the filing angles were determined and subjected to numerical simulations and experimental validation. The analysis focuses on optimizing the curtain coater for critical-flow-rate conditions, with the 26.4° angle demonstrating significant advantages in enhancing curtain integration. This angle reduced the threshold flow rate for stable curtain formation, improving mass flow rate consistency and dynamic pressure while minimizing turbulence kinetic energy. Additionally, the 26.4° filing angle minimized thickness variations along the curtain, preventing gradient-induced breakups and enhancing uniformity. The results offer a theoretical foundation for improving curtain coating efficiency and quality in industrial applications. Experimental data corroborated the numerical predictions, confirming the reliability of the simulation model.

Reducing vessel resistance by using ventilated cavities has been a highly researched topic in the marine industry. There is limited literature on ventilated supercavities near the free surface, which indicates that their dynamic behavior is more complex than conventional ventilated cavities due to the effect of the free surface. This paper employs numerical simulations to study the dynamic behavior of the ventilated supercavity, taking into account the effect of the free surface. Numerical simulations can predict gas leakage behaviors, cavity geometry, and internal flow structures. The influence of the free surface shortens the length of the ventilated cavity and increases the diameter. The presence of the free surface mainly changes the vertical velocity distribution between the free surface and the cavity. The results show that there are two typical gas leakage mechanisms under different immersion depths: twin-vortex tube leakage mode and re-entrant jet leakage mode. The internal flow field of ventilated supercavity is classified into three regions: the internal boundary layer, the ventilation influence region, and the reverse flow region. As the distance between the free surface and the ventilated supercavity decreases, the ventilated supercavity is affected by both the free surface effect and the gravity effect.

Zeng, C.-S.; Zhan, J.-M., and Hu, W.-Q., 2022. Numerical study on compound-slope seawalls with different types of protective facings. Journal of Coastal Research, 38(1), 182–195. Coconut Creek (Florida), ISSN 0749-0208. The compound seawall is an important infrastructure to protect the coast effectively against tide and wave impacts. In this paper, a hybrid realizable k – ∊/laminar model and a volume of fluid interface capture method were used to study compound-slope seawalls with different types of protective facings. An analytical method was used to separate the incident wave and the reflected wave, and the numerical results for a compound-slope seawall with a hollow-block protective facing structure were verified by experimental results. The monitored wave surface, incident wave, and reflected wave data in the numerical simulation were compared with the experimental results, and the results show that the numerical model can simulate the interaction process of waves and compound-slope seawalls well. Furthermore, a series of numerical simulation studies on compound-slope seawalls under different protective facing structures with different wave heights, wave periods, water depths, and structure slopes was conducted. The results show that the hollow-block protective facings have a significant weakening effect on the reflected wave height, wave run-up, and wave force when the wave is moderate, which is important for the safety of seawall and onshore building structures.

In this study, we simulate the acceleration-induced cavity bubble expansion and its non-spherical collapse in a drastically varying pressure field caused by mechanical impact, and we qualitatively compare the results with those for similar ζ number (Obreschkow et al., 2011 ) as recorded by a high-speed camera (Taylor, 2012 ). The gas–liquid interface is tracked by using the volume of fluid method. The nonlinear compressibility effect of the liquid phase is considered by applying the Tait equation. The simulation of the impact load is accomplished by converting the acceleration curve obtained from the experiment (Kang & Raphael, 2018 ) into the velocity curve of the bottom boundary movement through integration and subsequent using of dynamic mesh model. Numerical results show that cavitation bubble nucleuse expand rapidly in the drastically decreasing pressure field caused by the impact and a pressure wave is emitted and propagates in the liquid during the subsequent collapse of the bubble. When the pressure wave is reflected on the wall, it causes a high peak pressure at the wall surface, which may underlie the rupture of the bottle wall in the experiment (Daily & Pendlebury, 2014 ).

Film cooling using coolant jets is effective for increasing the cooling effectiveness of turbines. In the present study, large eddy simulation was employed for predicting small-scale vortices in the film-cooling process with different blowing ratios (BRs). The counter-rotating vortex pair (CRVP) was compared with the hairpin vortex, and results indicated the CRVP was the cross section of hairpin vortex. The results of a spectral analysis indicated a high correlation between the shedding period of the CRVP and the film-cooling effectiveness, and the dominant frequencies of the temperature and vorticity spectra were both identical to the shedding frequency of the CRVP when BR is less than 0.75. Furthermore, a higher shedding frequency of CRVP will suck the hot cross-flow into the core region more frequently, which will lead to a worse film-cooling effectiveness.