The article studies the oscillation features of the water in the square moon pool under the circumstances of wave-flow combined conditions. Comparing with the results of experiments of the square moon pool, a series o...The article studies the oscillation features of the water in the square moon pool under the circumstances of wave-flow combined conditions. Comparing with the results of experiments of the square moon pool, a series of studies reveal that the water piston oscillation phenomenon is quite similar to that of the circular one. Two types of oscillation are exhibited under different incoming wave periods, i.e. self-excited oscillation and forced oscillation. The difference between the circular and square moon pool is that the attack angle makes greater influences on the square one. "Beating phenomenon" is also found in the square moon pool which is not mentioned of the circular one.展开更多
为了拓展水面防波堤的有效消波周期范围,本文应用Bragg共振,开展多重水面穿透箱体与潜堤组合结构物的消波性能研究。基于时域势流理论,采用去奇异边界元方法(Desingularized Boundary Integral Equation Method,DBIEM),建立数值波浪水槽...为了拓展水面防波堤的有效消波周期范围,本文应用Bragg共振,开展多重水面穿透箱体与潜堤组合结构物的消波性能研究。基于时域势流理论,采用去奇异边界元方法(Desingularized Boundary Integral Equation Method,DBIEM),建立数值波浪水槽,数值计算了规则波与多重等间距布置的水面箱体与水底潜堤组合的结构物之间的相互作用。通过反射系数和透射系数分析了组合结构物的Bragg共振发生点位置、反射强度和消波性能。通过将数值结果与文献数据进行比较,验证了本文数值计算方法的有效性。计算结果给出了透射系数和反射系数随2S/λ(S为相邻结构物的中心间距,λ为入射波长)的变化趋势。结果表明,规则波在多重结构物中传播时会发生Bragg共振,此时其对波浪的衰减效果明显优于单体结构物。对于多重结构物,随着其数量、宽度、水面箱体浸深的增加,Bragg共振反射强度增加,不仅降低了透射系数,而且提升了对长周期波浪的消波能力;而增加相邻组合结构物间隙拓宽了有效消减波浪的周期范围。潜堤的存在加强了防波堤对长周期波的消浪能力。本研究为组合形式的防波堤设计提供参考。展开更多
段塞流引起的不稳定流体力使得立管振动更为复杂。基于VOF(volume of fluid)多相流模型对气液变化进行追踪,通过单向流固耦合方法得到含段塞流的缓波形立管振动响应。探究由表观液速引起的气液比变化对立管高曲率位置振动响应的影响,通...段塞流引起的不稳定流体力使得立管振动更为复杂。基于VOF(volume of fluid)多相流模型对气液变化进行追踪,通过单向流固耦合方法得到含段塞流的缓波形立管振动响应。探究由表观液速引起的气液比变化对立管高曲率位置振动响应的影响,通过时域和频域的分析发现:随着气液比的增大,立管顺流向和垂向位移先增后减并表现为驻波特性,而横流向位移先减后增,测点相位差体现行波特性。频率方面,横流向不同测点的主振频率不同。随气液比的增大,一阶和二阶频率对位移贡献的差值减小,模态竞争加剧。研究结果可为立管流致振动研究提供参考。展开更多
Through a simple review of low-frequency variation of blocking pattern and diagnoses of observational data and combining some experience in forecast practice,we put forward some thought about the mechanism of formatio...Through a simple review of low-frequency variation of blocking pattern and diagnoses of observational data and combining some experience in forecast practice,we put forward some thought about the mechanism of formation and maintenance of the blocking flow pattern from the synoptic/climatological point of view,It is emphasized that eastward moving and deepening of troughs in the upstream of the blocking high,the SST anomalies and topography effect are the main factors of impelling the variation of the blocking high.During the maintenance of Ural blocking high wave-flow interactions are studied through disposition of baroclinic trough(transient wave)and the blocking flow.This study will offer a primary basis for the further theoretical study on the formation mechanism of the blocking high.展开更多
基金support of "111" project which was from China Education Department( No. B07019)
文摘The article studies the oscillation features of the water in the square moon pool under the circumstances of wave-flow combined conditions. Comparing with the results of experiments of the square moon pool, a series of studies reveal that the water piston oscillation phenomenon is quite similar to that of the circular one. Two types of oscillation are exhibited under different incoming wave periods, i.e. self-excited oscillation and forced oscillation. The difference between the circular and square moon pool is that the attack angle makes greater influences on the square one. "Beating phenomenon" is also found in the square moon pool which is not mentioned of the circular one.
文摘为了拓展水面防波堤的有效消波周期范围,本文应用Bragg共振,开展多重水面穿透箱体与潜堤组合结构物的消波性能研究。基于时域势流理论,采用去奇异边界元方法(Desingularized Boundary Integral Equation Method,DBIEM),建立数值波浪水槽,数值计算了规则波与多重等间距布置的水面箱体与水底潜堤组合的结构物之间的相互作用。通过反射系数和透射系数分析了组合结构物的Bragg共振发生点位置、反射强度和消波性能。通过将数值结果与文献数据进行比较,验证了本文数值计算方法的有效性。计算结果给出了透射系数和反射系数随2S/λ(S为相邻结构物的中心间距,λ为入射波长)的变化趋势。结果表明,规则波在多重结构物中传播时会发生Bragg共振,此时其对波浪的衰减效果明显优于单体结构物。对于多重结构物,随着其数量、宽度、水面箱体浸深的增加,Bragg共振反射强度增加,不仅降低了透射系数,而且提升了对长周期波浪的消波能力;而增加相邻组合结构物间隙拓宽了有效消减波浪的周期范围。潜堤的存在加强了防波堤对长周期波的消浪能力。本研究为组合形式的防波堤设计提供参考。
文摘段塞流引起的不稳定流体力使得立管振动更为复杂。基于VOF(volume of fluid)多相流模型对气液变化进行追踪,通过单向流固耦合方法得到含段塞流的缓波形立管振动响应。探究由表观液速引起的气液比变化对立管高曲率位置振动响应的影响,通过时域和频域的分析发现:随着气液比的增大,立管顺流向和垂向位移先增后减并表现为驻波特性,而横流向位移先减后增,测点相位差体现行波特性。频率方面,横流向不同测点的主振频率不同。随气液比的增大,一阶和二阶频率对位移贡献的差值减小,模态竞争加剧。研究结果可为立管流致振动研究提供参考。
基金National Natural Science Foundation of China under Grant No.49675257.
文摘Through a simple review of low-frequency variation of blocking pattern and diagnoses of observational data and combining some experience in forecast practice,we put forward some thought about the mechanism of formation and maintenance of the blocking flow pattern from the synoptic/climatological point of view,It is emphasized that eastward moving and deepening of troughs in the upstream of the blocking high,the SST anomalies and topography effect are the main factors of impelling the variation of the blocking high.During the maintenance of Ural blocking high wave-flow interactions are studied through disposition of baroclinic trough(transient wave)and the blocking flow.This study will offer a primary basis for the further theoretical study on the formation mechanism of the blocking high.
