Dubrovin establishes a certain relationship between the GUE partition function and the partition function of Gromov-Witten invariants of the complex projective line.In this paper,we give a direct proof of Dubrovin’s ...Dubrovin establishes a certain relationship between the GUE partition function and the partition function of Gromov-Witten invariants of the complex projective line.In this paper,we give a direct proof of Dubrovin’s result.We also present in a diagram the recent progress on topological gravity and matrix gravity.展开更多
As a part of boundaries for a free curved surface of a Pelton bucket,the cutout is indispensable to secure the smooth entrance of the unsteady inflow of water jet into the rotating bucket.The cutout of the rotating bu...As a part of boundaries for a free curved surface of a Pelton bucket,the cutout is indispensable to secure the smooth entrance of the unsteady inflow of water jet into the rotating bucket.The cutout of the rotating bucket unsteadily separates a free jet into two branches in both space and time:the impinging branch landing on the relevant bucket surface,and the flow-off branch separated by the cutout toward the preceding bucket.In order to investigate the unsteady jet separation by the cutout three-dimensionally,a semicircular free jet was discretized into 641 nodes of boundary-fitted grids.The position P of impinging jet branch landing on the bucket surface was acquired with the relative velocity W and the water depth D at each node.The trailing edge surface of the flow-off jet branch was simultaneously computed unsteadily.The complicate unsteady interaction of the bucket cutout with the branched free jets was clarified visually with the 3D view of illustrations in order to research the unsteady hydraulic performance of Pelton turbines in space and time.展开更多
以G往关于电喷雾过程仿真研究对象多局限于低电导率液体,而电喷雾推力器使用的工质主要为高电导率离子液体,推力器工作时,离子液体在强电场作用下形成锥形,并在末端发射出锥形等离子体荷电喷雾。但离子液体受空间电荷、液体内部电流及...以G往关于电喷雾过程仿真研究对象多局限于低电导率液体,而电喷雾推力器使用的工质主要为高电导率离子液体,推力器工作时,离子液体在强电场作用下形成锥形,并在末端发射出锥形等离子体荷电喷雾。但离子液体受空间电荷、液体内部电流及液面电流的影响较大,电流体力学过程更为复杂,相关仿真研究极为匮乏。本文通过加入未简化的电荷守恒方程,考虑空间电荷及电流对锥射流形成与演化的影响,并耦合高斯定律和Navier-Stokes(N-S)方程求解流场及电荷分布,使用volume of fluid(VOF:流体体积)方法追踪液-气界面的变化,对高电导率液体的电喷雾锥射流形成过程开展了仿真研究。本次仿真工作以庚烷为工质模拟了锥射流形成与演化过程,得到电荷、电势和流场的分布,并与未考虑空间电荷的理想电介质模型进行对比。仿真结果表明,在低电导率情况下,本文模型与理想电介质模型的结果相近;高电导率情况下,本文模型得到的结果与相关实验更加吻合。展开更多
The acceleration mechanism of astrophysical jet and the collimation mechanism narrowing down to a long distance have been examined so far. It is a collimation problem of how to narrow the astrophysical jet narrowly. F...The acceleration mechanism of astrophysical jet and the collimation mechanism narrowing down to a long distance have been examined so far. It is a collimation problem of how to narrow the astrophysical jet narrowly. Further, the model of the astrophysical jet acceleration mechanism is required to solve this collimation problem at the same time as well as its acceleration. At the present time, the magnetic force model （magnetic centrifugal force and magnetic pressure） is regarded as the most dominant theory which solves the two problems of astrophysical jet acceleration and collimation at the same time. In addition to the present astrophysical jet narrow collimation mechanism by magnetic tension （pinch） force, in this article, another collimation mechanism which narrows down an astrophysical jet is newly introduced. That is, since a curvature is generated in the space around the astrophysical jet by magnetic field, a kind of pressure equivalent to the gravitational effect is generated in the direction of the interior of astrophysical jet as well as the pinch force from the outer circumferential surface of the astrophysical jet.展开更多
文摘Dubrovin establishes a certain relationship between the GUE partition function and the partition function of Gromov-Witten invariants of the complex projective line.In this paper,we give a direct proof of Dubrovin’s result.We also present in a diagram the recent progress on topological gravity and matrix gravity.
基金supported by the National Natural Science Foundation of China(Grant No.50379015)the Major Science and Technology Projects in Zhejiang province(Grant No.2008C11057)
文摘As a part of boundaries for a free curved surface of a Pelton bucket,the cutout is indispensable to secure the smooth entrance of the unsteady inflow of water jet into the rotating bucket.The cutout of the rotating bucket unsteadily separates a free jet into two branches in both space and time:the impinging branch landing on the relevant bucket surface,and the flow-off branch separated by the cutout toward the preceding bucket.In order to investigate the unsteady jet separation by the cutout three-dimensionally,a semicircular free jet was discretized into 641 nodes of boundary-fitted grids.The position P of impinging jet branch landing on the bucket surface was acquired with the relative velocity W and the water depth D at each node.The trailing edge surface of the flow-off jet branch was simultaneously computed unsteadily.The complicate unsteady interaction of the bucket cutout with the branched free jets was clarified visually with the 3D view of illustrations in order to research the unsteady hydraulic performance of Pelton turbines in space and time.
文摘以G往关于电喷雾过程仿真研究对象多局限于低电导率液体,而电喷雾推力器使用的工质主要为高电导率离子液体,推力器工作时,离子液体在强电场作用下形成锥形,并在末端发射出锥形等离子体荷电喷雾。但离子液体受空间电荷、液体内部电流及液面电流的影响较大,电流体力学过程更为复杂,相关仿真研究极为匮乏。本文通过加入未简化的电荷守恒方程,考虑空间电荷及电流对锥射流形成与演化的影响,并耦合高斯定律和Navier-Stokes(N-S)方程求解流场及电荷分布,使用volume of fluid(VOF:流体体积)方法追踪液-气界面的变化,对高电导率液体的电喷雾锥射流形成过程开展了仿真研究。本次仿真工作以庚烷为工质模拟了锥射流形成与演化过程,得到电荷、电势和流场的分布,并与未考虑空间电荷的理想电介质模型进行对比。仿真结果表明,在低电导率情况下,本文模型与理想电介质模型的结果相近;高电导率情况下,本文模型得到的结果与相关实验更加吻合。
文摘The acceleration mechanism of astrophysical jet and the collimation mechanism narrowing down to a long distance have been examined so far. It is a collimation problem of how to narrow the astrophysical jet narrowly. Further, the model of the astrophysical jet acceleration mechanism is required to solve this collimation problem at the same time as well as its acceleration. At the present time, the magnetic force model （magnetic centrifugal force and magnetic pressure） is regarded as the most dominant theory which solves the two problems of astrophysical jet acceleration and collimation at the same time. In addition to the present astrophysical jet narrow collimation mechanism by magnetic tension （pinch） force, in this article, another collimation mechanism which narrows down an astrophysical jet is newly introduced. That is, since a curvature is generated in the space around the astrophysical jet by magnetic field, a kind of pressure equivalent to the gravitational effect is generated in the direction of the interior of astrophysical jet as well as the pinch force from the outer circumferential surface of the astrophysical jet.
