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River runoff plays an important role in watershed ecosystems and human survival, and it is controlled by multiple environmental factors. However, the synergistic effects of various large-scale circulation factors and meteorological factors on the runoff on different time-frequency scales have rarely been explored. In light of this, the underlying mechanism of the synergistic effects of the different environmental factors on the runoff variations was investigated in the Yellow River Basin of China during the period 1950–2019 using the bivariate wavelet coherence (WTC) and multiple wavelet coherence (MWC) methods. First, the continuous wavelet transform (CWT) method was used to analyze the multiscale characteristics of the runoff. The results of the CWT indicate that the runoff exhibited significant continuous or discontinuous annual and semiannual oscillations during the study period. Scattered inter-annual time scales were also observed for the runoff in the Yellow River Basin. The meteorological factors better explained the runoff variations on seasonal and annual time scales. The average wavelet coherence (AWC) and the percent area of the significant coherence (PASC) between the runoff and individual meteorological factors were 0.454 and 19.89%, respectively. The circulation factors mainly regulated the runoff on the inter-annual and decadal time scales with more complicated phase relationships due to their indirect effects on the runoff. The AWC and PASC between the runoff and individual circulation factors were 0.359 and 7.31%, respectively. The MWC analysis revealed that the synergistic effects of multiple factors should be taken into consideration to explain the multiscale characteristic variations of the runoff. The AWC or MWC ranges were 0.320–0.560, 0.617–0.755, and 0.819–0.884 for the combinations of one, two, and three circulation and meteorological factors, respectively. The PASC ranges were 3.53%–33.77%, 12.93%–36.90%, and 20.67%–39.34% for the combinations one, two, and three driving factors, respectively. The combinations of precipitation, evapotranspiration (or the number of rainy days), and the Arctic Oscillation performed well in explaining the variability in the runoff on all time scales, and the average MWC and PASC were 0.847 and 28.79%, respectively. These findings are of great significance for improving our understanding of hydro-climate interactions and water resources prediction in the Yellow River Basin.
Junjie Wang; Bing Shi; Enjin Zhao; Xuguang Chen; Shaopeng Yang. Synergistic effects of multiple driving factors on the runoff variations in the Yellow River Basin, China. Journal of Arid Land 2021, 1 -23.
AMA StyleJunjie Wang, Bing Shi, Enjin Zhao, Xuguang Chen, Shaopeng Yang. Synergistic effects of multiple driving factors on the runoff variations in the Yellow River Basin, China. Journal of Arid Land. 2021; ():1-23.
Chicago/Turabian StyleJunjie Wang; Bing Shi; Enjin Zhao; Xuguang Chen; Shaopeng Yang. 2021. "Synergistic effects of multiple driving factors on the runoff variations in the Yellow River Basin, China." Journal of Arid Land , no. : 1-23.
Laboratory experiments are presented to investigate the effect of different piggyback pipeline configurations on the morphology of local scour under wave conditions. Scour depth and width around the pipelines under regular and irregular waves are measured and analyzed for a range of pipeline and wave conditions; such as the spacing between two pipes (G), gap between the main pipe and seabed (e), pipe diameter (D), wave height (H) and period (T). Experimental results reveal that both the scour depth and width around piggyback pipeline is much larger than those around single pipe under the same wave conditions. Scour depth increases with the increase of the Keulegan-Carpenter (KC) number and decreases with increase of G and e. When e exceeds 0.5D, scour depth tends to approach 0. When spacing G is greater than 0.4D, the destabilization from small pipe to large one is greatly reduced, resulting in scour depth around piggyback pipeline being close to that around single pipe. Similar to scour depth, scour width broadens with the increase of KC number increasing and decreases with the increase of G. Experiments also show that the effect of e on scour depth is greater than that of G under the same test conditions, while their impact on scour width is opposite. Furthermore, scour width under irregular waves is extended slightly compared with regular wave for otherwise the identical conditions.
Shaopeng Yang; Bing Shi; Yakun Guo. Investigation on scour scale of piggyback pipeline under wave conditions. Ocean Engineering 2019, 182, 196 -202.
AMA StyleShaopeng Yang, Bing Shi, Yakun Guo. Investigation on scour scale of piggyback pipeline under wave conditions. Ocean Engineering. 2019; 182 ():196-202.
Chicago/Turabian StyleShaopeng Yang; Bing Shi; Yakun Guo. 2019. "Investigation on scour scale of piggyback pipeline under wave conditions." Ocean Engineering 182, no. : 196-202.
Submarine pipelines have been extensively used for marine oil and gas extraction due to their high efficiency, safety, and low price. However, submarine pipelines are vulnerable to extreme waves (i.e., tsunami waves). Previous research has often used solitary waves as a basis for studying the impacts of tsunami waves on submarine pipelines, although the hydrodynamic characteristics and wave properties drastically differ from those of real-world tsunami waves. This paper numerically investigates the hydrodynamic characteristics of tsunami waves interacting with submarine pipelines, but instead uses an improved wave model to generate a tsunami-like wave that more closely resembles those encountered in the real-world. The tsunami-like wave generated based on a real-world tsunami wave profile recorded during a 2011 tsunami in Japan has been applied. Given the same wave height, simulation results show that peak hydrodynamic forces of the tsunami-like wave are greater than those of the solitary wave. Meanwhile, the duration of the acting force under the tsunami-like wave is much longer than that of the solitary wave. These findings underline the basic reasons for the destructive power of tsunamis. It is also noted that the hydrodynamic forces of the pipeline under the tsunami-like wave increase with wave height, but will decrease as water depth increases. In addition to the single pipeline, the complicated hydrodynamic characteristics of pipelines in tandem arrangement have been also numerically studied. It is believed that the findings drawn from this paper can enhance our understanding of the induced forces on submarine pipelines under extreme tsunami waves.
Enjin Zhao; Ke Qu; Lin Mu; Simon Kraatz; Bing Shi. Numerical Study on the Hydrodynamic Characteristics of Submarine Pipelines under the Impact of Real-World Tsunami-Like Waves. Water 2019, 11, 221 .
AMA StyleEnjin Zhao, Ke Qu, Lin Mu, Simon Kraatz, Bing Shi. Numerical Study on the Hydrodynamic Characteristics of Submarine Pipelines under the Impact of Real-World Tsunami-Like Waves. Water. 2019; 11 (2):221.
Chicago/Turabian StyleEnjin Zhao; Ke Qu; Lin Mu; Simon Kraatz; Bing Shi. 2019. "Numerical Study on the Hydrodynamic Characteristics of Submarine Pipelines under the Impact of Real-World Tsunami-Like Waves." Water 11, no. 2: 221.
The interaction between coastal ocean flows and the submarine pipeline involved with distinct physical phenomena occurring at a vast range of spatial and temporal scales has always been an important research subject. In this article, the hydrodynamic forces on the submarine pipeline and the characteristics of tidal flows around the pipeline are studied depending on a high-fidelity multi-physics modeling system (SIFOM–FVCOM), which is an integration of the Solver for Incompressible Flow on the Overset Meshes (SIFOM) and the Finite Volume Coastal Ocean Model (FVCOM). The interactions between coastal ocean flows and the submarine pipeline are numerically simulated in a channel flume, the results of which show that the hydrodynamic forces on the pipeline increase with the increase of tidal amplitude and the decrease of water depth. Additionally, when scour happens under the pipeline, the numerical simulation of the suspended pipeline is also carried out, showing that the maximum horizontal hydrodynamic forces on the pipeline reduce and the vertical hydrodynamic forces grow with the increase of the scour depth. According to the results of the simulations in this study, an empirical formula for estimating the hydrodynamic forces on the submarine pipeline caused by coastal ocean flows is given, which might be useful in engineering problems. The results of the study also reveal the basic features of flow structures around the submarine pipeline and its hydrodynamic forces caused by tidal flows, which contributes to the design of submarine pipelines.
Enjin Zhao; Lin Mu; Bing Shi. Numerical Study of the Influence of Tidal Current on Submarine Pipeline Based on the SIFOM–FVCOM Coupling Model. Water 2018, 10, 1814 .
AMA StyleEnjin Zhao, Lin Mu, Bing Shi. Numerical Study of the Influence of Tidal Current on Submarine Pipeline Based on the SIFOM–FVCOM Coupling Model. Water. 2018; 10 (12):1814.
Chicago/Turabian StyleEnjin Zhao; Lin Mu; Bing Shi. 2018. "Numerical Study of the Influence of Tidal Current on Submarine Pipeline Based on the SIFOM–FVCOM Coupling Model." Water 10, no. 12: 1814.
Two-dimensional incompressible fluid flows over a periodically deforming circular cylinder are simulated with lattice Boltzmann method for Reynolds number 200. The periodic deformation is controlled by the ratios of deforming amplitude relative to the cylindrical radius and deforming frequency relative to natural vortex shedding frequency. The flow features are mainly decided by the periodic deformation. So three deforming amplitude ratios (0.05, 0.075, 0.1) are considered and deforming frequency ratios range from 0.75 to 2.0. The vortex structures are divided into three categories and two type transitional structures are observed. The correlation between vortex shedding patterns and periodic deformation is analyzed. In addition, the impact of periodic deformation to drag coefficient is studied. Numerical results show that special deformation can reduce the drag.
Haicheng Zheng; Bing Shi; Qian Yu; Enjin Zhao. Numerical study of flow over periodically deforming circular cylinder. Computers & Fluids 2016, 136, 348 -353.
AMA StyleHaicheng Zheng, Bing Shi, Qian Yu, Enjin Zhao. Numerical study of flow over periodically deforming circular cylinder. Computers & Fluids. 2016; 136 ():348-353.
Chicago/Turabian StyleHaicheng Zheng; Bing Shi; Qian Yu; Enjin Zhao. 2016. "Numerical study of flow over periodically deforming circular cylinder." Computers & Fluids 136, no. : 348-353.
This study proposes a new approach in which an impermeable plate is placed under the pipeline to prevent the local scour around the pipeline. In order to understand the performance of this approach, the finite volume method (FVM) and volume of fluid (VOF) method are adopted to simulate the flow field around the pipeline. The pressure distribution along the sandy bed surface is obtained by considering the variation of water surface. Furthermore, the effects of water depth, unidirectional and bidirectional impermeable plates on pressure difference are discussed. The seepage flow field of sandy bed near underwater pipeline is numerically simulated using the laminar and porous media model. On this basis, the effect of the impermeable plate length on hydraulic gradient is investigated and the critical length of impermeable plate is obtained. The simulated results show that when the water depth is smaller than 5.00D (D is the diameter of pipeline), the effect of the water depth on the pressure difference is remarkable. The pressure differences between two endpoints of both the unidirectional and bidirectional plates decrease with the increase of the plate length. The variations of the pressure differences for both the unidirectional and bidirectional plates are similar. With the increase of plate length, the hydraulic gradient decreases and the piping at the seepage exit is avoided effectively as long as it reaches a certain length. Such a critical length of the plate decreases with the increase of the water depth. When water depth is larger than 4.00D, the effect of the water depth on the critical length is small. For the same water depth, the critical length of impermeable plate increases with the increase of the dimensionless flow parameter. Numerical simulation results are in good agreement with the available experimental measurements.
Zhiyong Zhang; Bing Shi; Yakun Guo; Lipeng Yang. Numerical investigation on critical length of impermeable plate below underwater pipeline under steady current. Science China Technological Sciences 2013, 56, 1232 -1240.
AMA StyleZhiyong Zhang, Bing Shi, Yakun Guo, Lipeng Yang. Numerical investigation on critical length of impermeable plate below underwater pipeline under steady current. Science China Technological Sciences. 2013; 56 (5):1232-1240.
Chicago/Turabian StyleZhiyong Zhang; Bing Shi; Yakun Guo; Lipeng Yang. 2013. "Numerical investigation on critical length of impermeable plate below underwater pipeline under steady current." Science China Technological Sciences 56, no. 5: 1232-1240.