Mechanical energy input from atmosphere and losses from wave-breaking dissipation of sea surface waves are estimated by a direct scheme. This scheme is based on the integration in the wavenumber space of the wind inpu...Mechanical energy input from atmosphere and losses from wave-breaking dissipation of sea surface waves are estimated by a direct scheme. This scheme is based on the integration in the wavenumber space of the wind input and breaking dissipation source functions of the MASNUM wave model. The global amount of wind energy input, averaged in 2005, is about 57 TW, and the wave-breaking dissipation summed in deep-water is about 33 TW, over a half of the wind energy input. The residual may be dissipated by beach processes. Global distributions of the energy input and breaking dissipation concentrate in the westerlies of the Southern Hemisphere.展开更多
Precipitation over southeastern Lake Baikal features a significant decreasing trend in July and August over 1979–2018 and is closely related to blocking occurrence over central Siberia(45°–70°N,75°–1...Precipitation over southeastern Lake Baikal features a significant decreasing trend in July and August over 1979–2018 and is closely related to blocking occurrence over central Siberia(45°–70°N,75°–115°E).This study investigates the formation and maintenance of anticyclonic and cyclonic wave-breaking(AWB and CWB)blocking events and their climate impacts on precipitation in the southeastern Lake Baikal area.Both AWB and CWB blocking events are characterized by a cold trough deepening from the sub-Arctic region and a ridge amplifying toward its north over central Siberia,as well as an evident Rossby wave train over midlatitude Eurasia.For AWB blocking events,the ridge and trough pair tilts clockwise and the wave train exhibits a zonal distribution.In contrast,ridge and trough pair associated with CWB blocking events leans anticlockwise with larger-scale,meridional,and more anisotropic signatures.Moreover,the incoming Rossby wave energy associated with CWB blocking events is more evident than for AWB blocking events.Therefore,CWB blocking events are more persistent.AWB blocking events produce more extensive and persistent precipitation over the southeastern Lake Baikal area than CWB blocking events,in which moderate above-normal rainfall is seen in the decaying periods of blockings.A significant decreasing trend is found in terms of AWB blocking occurrence over central Siberia,which may contribute to the downward trend of precipitation over southeastern Lake Baikal.展开更多
The space-time evolution of a given density perturbation in cold homogeneous electron- positron-ion plasma is investigated with an assumption of infinitely massive ions by employing a numerical calculation method. The...The space-time evolution of a given density perturbation in cold homogeneous electron- positron-ion plasma is investigated with an assumption of infinitely massive ions by employing a numerical calculation method. The phase-mixing time and wave-breaking time can be effectively distinguished with this method. It is found that an increase of the ratio of equilibrium ion density to equilibrium electron density can attenuate plasma oscillations, leading to a delay in wave breaking. The dependence of the phase-mixing and wave-breaking times on the amplitude of the initial perturbation is also discussed.展开更多
We focus on the blow-up phenomena of Cauchy problem for the Camassa-Holm equation. Blow-up can occur only in the form of wave-breaking, i.e. the solution is bounded but its slope becomes unbounded in finite time. We p...We focus on the blow-up phenomena of Cauchy problem for the Camassa-Holm equation. Blow-up can occur only in the form of wave-breaking, i.e. the solution is bounded but its slope becomes unbounded in finite time. We proved that there is such a point that its slope becomes infinite exactly at breaking time. We also gave the precise blow-up rate and the blow-up set.展开更多
为缓和浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)晃动时液化石油气(Liquefied Petroleum Gas,LPG)大型储罐内的液体介质对壳体的冲击影响,在LPG储罐内设置破浪板。采用计算流体力学(Computational Fluid Dy...为缓和浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)晃动时液化石油气(Liquefied Petroleum Gas,LPG)大型储罐内的液体介质对壳体的冲击影响,在LPG储罐内设置破浪板。采用计算流体力学(Computational Fluid Dynamics,CFD)软件分析破浪板对流体晃动的抑制作用并进行受力计算。利用流体体积(Volume of Fluid,VOF)气液两相模型建立六面体与四面体网格混合划分模型,通过CFD的动网格功能模拟船体晃动。结果表明,选取的数值计算模型与试验结果吻合较好。数值模拟结果表明设置破浪板能够有效降低晃动幅度,稳定气液界面,稳定压力分布和波动,减小罐体受液体冲击力,从而确保LPG储罐在FPSO上的使用安全。展开更多
基金the Key project of the National Natural Science Foundation of China under contract 40730842
文摘Mechanical energy input from atmosphere and losses from wave-breaking dissipation of sea surface waves are estimated by a direct scheme. This scheme is based on the integration in the wavenumber space of the wind input and breaking dissipation source functions of the MASNUM wave model. The global amount of wind energy input, averaged in 2005, is about 57 TW, and the wave-breaking dissipation summed in deep-water is about 33 TW, over a half of the wind energy input. The residual may be dissipated by beach processes. Global distributions of the energy input and breaking dissipation concentrate in the westerlies of the Southern Hemisphere.
基金supported by the National Science and Technology Support Program of China (Grant No. 2015BAC03B03)the National Natural Science Foundation of China (Grant Nos. 41861144014, 41630424 and 41875078)
文摘Precipitation over southeastern Lake Baikal features a significant decreasing trend in July and August over 1979–2018 and is closely related to blocking occurrence over central Siberia(45°–70°N,75°–115°E).This study investigates the formation and maintenance of anticyclonic and cyclonic wave-breaking(AWB and CWB)blocking events and their climate impacts on precipitation in the southeastern Lake Baikal area.Both AWB and CWB blocking events are characterized by a cold trough deepening from the sub-Arctic region and a ridge amplifying toward its north over central Siberia,as well as an evident Rossby wave train over midlatitude Eurasia.For AWB blocking events,the ridge and trough pair tilts clockwise and the wave train exhibits a zonal distribution.In contrast,ridge and trough pair associated with CWB blocking events leans anticlockwise with larger-scale,meridional,and more anisotropic signatures.Moreover,the incoming Rossby wave energy associated with CWB blocking events is more evident than for AWB blocking events.Therefore,CWB blocking events are more persistent.AWB blocking events produce more extensive and persistent precipitation over the southeastern Lake Baikal area than CWB blocking events,in which moderate above-normal rainfall is seen in the decaying periods of blockings.A significant decreasing trend is found in terms of AWB blocking occurrence over central Siberia,which may contribute to the downward trend of precipitation over southeastern Lake Baikal.
基金supported by National Natural Science Foundation of China (Nos. 11665012 and 11247016)the Natural Science Foundation of Jiangxi Province, China (Nos. 2014ZBAB202001 and 2015ZBAB202006)
文摘The space-time evolution of a given density perturbation in cold homogeneous electron- positron-ion plasma is investigated with an assumption of infinitely massive ions by employing a numerical calculation method. The phase-mixing time and wave-breaking time can be effectively distinguished with this method. It is found that an increase of the ratio of equilibrium ion density to equilibrium electron density can attenuate plasma oscillations, leading to a delay in wave breaking. The dependence of the phase-mixing and wave-breaking times on the amplitude of the initial perturbation is also discussed.
基金Supported by the National Natural Science Foun-dation of China (10131050) Science and Technology Committee of Shanghai ,China (03JC14013)
文摘We focus on the blow-up phenomena of Cauchy problem for the Camassa-Holm equation. Blow-up can occur only in the form of wave-breaking, i.e. the solution is bounded but its slope becomes unbounded in finite time. We proved that there is such a point that its slope becomes infinite exactly at breaking time. We also gave the precise blow-up rate and the blow-up set.
文摘为缓和浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)晃动时液化石油气(Liquefied Petroleum Gas,LPG)大型储罐内的液体介质对壳体的冲击影响,在LPG储罐内设置破浪板。采用计算流体力学(Computational Fluid Dynamics,CFD)软件分析破浪板对流体晃动的抑制作用并进行受力计算。利用流体体积(Volume of Fluid,VOF)气液两相模型建立六面体与四面体网格混合划分模型,通过CFD的动网格功能模拟船体晃动。结果表明,选取的数值计算模型与试验结果吻合较好。数值模拟结果表明设置破浪板能够有效降低晃动幅度,稳定气液界面,稳定压力分布和波动,减小罐体受液体冲击力,从而确保LPG储罐在FPSO上的使用安全。
