In order to establish a well-balanced scheme, 2D shallow water equations were transformed and solved by using the Finite Volume Method （FVM） with unstructured mesh. The numerical flux from the interface between cell...In order to establish a well-balanced scheme, 2D shallow water equations were transformed and solved by using the Finite Volume Method （FVM） with unstructured mesh. The numerical flux from the interface between cells was computed with an exact Riemann solver, and the improved dry Riemann solver was applied to deal with the wet/dry problems. The model was verified through computing some typical examples and the tidal bore on the Qiantang River. The results show that the scheme is robust and accurate, and could be applied extensively to engineering problems.展开更多
For a heavy hydrostatic bearing with a high linear velocity, the results of numerical calculations often differ from practical conditions if the viscosity is considered as constant. In this article, the influence of t...For a heavy hydrostatic bearing with a high linear velocity, the results of numerical calculations often differ from practical conditions if the viscosity is considered as constant. In this article, the influence of the oil cavity depth on the temperature field in the heavy hydrostatic bearing is discussed in the context of variable viscosity. The viscosity-temperature relations for the gap oil film are first established by fitting B-Spline curves, then, numerical calculations for the temperature field in the heavy hydrostatic bearing of different oil cavity depths are carried out based on Finite Volume Method （FVM） under the same rotating speed, and the influence of the oil cavity depth on the temperature distribution in the gap oil film of the hydrostatic bearing is discussed. The results of numerical calculations provide the temperature distribution state inside the hydrostatic bearing, which would help the selection and the design of hydrostatic bearings in engineering practice.展开更多
To study the heavy hydrostatic bearing with multiple oil pads, a reasonably simplified model of the pad is put forward, and the mathematical model of the bearing characteristics of the multiple oil pad hydrostatic bea...To study the heavy hydrostatic bearing with multiple oil pads, a reasonably simplified model of the pad is put forward, and the mathematical model of the bearing characteristics of the multiple oil pad hydrostatic bearing is built with consideration of variable viscosity. The pressure field in the clearance oil film of the hydrostatic bearing at various velocities is simulated based on the Finite Volume Method （FVM） by using the software of Computational Fluid Dynamics （CFD）. Some pressure experiments on the hydrostatic bearing were carried out and the results verified the rationality of the simplified model of the pad and the validity of the numerical simulation. It is concluded that the viscosity has a great influence on the pressure in the heavy hydrostatic bearing and cannot be neglected, especially, in cases of high rotating speed. The results of numerical calculations provide the internal flow states inside the bearing, which would help the design of the oil cavity structure of the bearing in engineering practice.展开更多
The modified QUICK scheme on unstructured grid was used to improve the advection flux approximation, and the depth-averaged κ-ε turbulence model with the scheme based on FVM by SIMPLE series algorithm was establishe...The modified QUICK scheme on unstructured grid was used to improve the advection flux approximation, and the depth-averaged κ-ε turbulence model with the scheme based on FVM by SIMPLE series algorithm was established and applied to spur-dike flow computation. In this model, the over-relaxed approach was adopted to estimate the diffusion flux in view of its advantages in reducing errors and sustaining numerical stability usually encountered in non-orthogonal meshes. Two spur-dike cases with different defection angles （90°and 135°） were analyzed to validate the model. Computed results show that the predicted velocities and recirculation lengths are in good agreement with the observed data. Moreover, the computations on structured and unstructured grids were compared in terms of the approximately equivalent grid numbers. It can be concluded that the precision with unstructured grids is higher than that with structured grids in spite that the CPU time required is slightly more with unstructured grids Thus, it is significant to apply the method to numerical simulation of practical hydraulic engineering.展开更多
The Chinese sturgeon （Acipenser Sinensis） is one of the unique and important fishery resources in China. Since the construction of the Gezhouba Dam, the traditional migration route of the sturgeon has been blocked; ...The Chinese sturgeon （Acipenser Sinensis） is one of the unique and important fishery resources in China. Since the construction of the Gezhouba Dam, the traditional migration route of the sturgeon has been blocked; consequently, the length of natural spawning sites is reduced from 800 km in the past to less than 5 km at present. As an endangered species, the Chinese sturgeon has become one of the most conserved aquatic species. In this article, the flow field of its spawning states in the downstream of Gezhouba Dam was simulated and analyzed using N-S equations and k-ε turbulence model. Volume Of Fluid （VOF） method with the Finite Volume Method （FVM） was used to simulate the water-air two-phase flow to examine the computed area. On the basis of the ecological-hydraulic characteristics of Chinese sturgeon, the features of the flow field were investigated to provide theoretical support for the proper management of the Three Gorges Reservoir.展开更多
基金Project supported by the Natural Science Foundation of Zhejiang Province (Grant No: M403054).
文摘In order to establish a well-balanced scheme, 2D shallow water equations were transformed and solved by using the Finite Volume Method （FVM） with unstructured mesh. The numerical flux from the interface between cells was computed with an exact Riemann solver, and the improved dry Riemann solver was applied to deal with the wet/dry problems. The model was verified through computing some typical examples and the tidal bore on the Qiantang River. The results show that the scheme is robust and accurate, and could be applied extensively to engineering problems.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50975066,51075106)the National Natural Science Funds for Young Scholars of China(Grant No. 51005063)
文摘For a heavy hydrostatic bearing with a high linear velocity, the results of numerical calculations often differ from practical conditions if the viscosity is considered as constant. In this article, the influence of the oil cavity depth on the temperature field in the heavy hydrostatic bearing is discussed in the context of variable viscosity. The viscosity-temperature relations for the gap oil film are first established by fitting B-Spline curves, then, numerical calculations for the temperature field in the heavy hydrostatic bearing of different oil cavity depths are carried out based on Finite Volume Method （FVM） under the same rotating speed, and the influence of the oil cavity depth on the temperature distribution in the gap oil film of the hydrostatic bearing is discussed. The results of numerical calculations provide the temperature distribution state inside the hydrostatic bearing, which would help the selection and the design of hydrostatic bearings in engineering practice.
基金supported by the National Natural Science Funds for Young Scholar of China(Grant No.51005063)the Heilongjiang Postdoctoral Science-Research Foundation(GrantLBH-Q12062)the National Natural Science Foundation of China(Grant No.51075106)
文摘To study the heavy hydrostatic bearing with multiple oil pads, a reasonably simplified model of the pad is put forward, and the mathematical model of the bearing characteristics of the multiple oil pad hydrostatic bearing is built with consideration of variable viscosity. The pressure field in the clearance oil film of the hydrostatic bearing at various velocities is simulated based on the Finite Volume Method （FVM） by using the software of Computational Fluid Dynamics （CFD）. Some pressure experiments on the hydrostatic bearing were carried out and the results verified the rationality of the simplified model of the pad and the validity of the numerical simulation. It is concluded that the viscosity has a great influence on the pressure in the heavy hydrostatic bearing and cannot be neglected, especially, in cases of high rotating speed. The results of numerical calculations provide the internal flow states inside the bearing, which would help the design of the oil cavity structure of the bearing in engineering practice.
基金the National Nature Science Foundation of China (Grant Nos. 50679019 and 50009001)the National Basic Research Program of China (973 Program, Grant No. 2008CB418202)the Social Technology Development Foundation of Jiangsu Province (Grant No.BS2006095)
文摘The modified QUICK scheme on unstructured grid was used to improve the advection flux approximation, and the depth-averaged κ-ε turbulence model with the scheme based on FVM by SIMPLE series algorithm was established and applied to spur-dike flow computation. In this model, the over-relaxed approach was adopted to estimate the diffusion flux in view of its advantages in reducing errors and sustaining numerical stability usually encountered in non-orthogonal meshes. Two spur-dike cases with different defection angles （90°and 135°） were analyzed to validate the model. Computed results show that the predicted velocities and recirculation lengths are in good agreement with the observed data. Moreover, the computations on structured and unstructured grids were compared in terms of the approximately equivalent grid numbers. It can be concluded that the precision with unstructured grids is higher than that with structured grids in spite that the CPU time required is slightly more with unstructured grids Thus, it is significant to apply the method to numerical simulation of practical hydraulic engineering.
基金Project supported by the Three Georges Construction Commission and the National Natural Science Foundation of China (Grant No. 30490231).
文摘The Chinese sturgeon （Acipenser Sinensis） is one of the unique and important fishery resources in China. Since the construction of the Gezhouba Dam, the traditional migration route of the sturgeon has been blocked; consequently, the length of natural spawning sites is reduced from 800 km in the past to less than 5 km at present. As an endangered species, the Chinese sturgeon has become one of the most conserved aquatic species. In this article, the flow field of its spawning states in the downstream of Gezhouba Dam was simulated and analyzed using N-S equations and k-ε turbulence model. Volume Of Fluid （VOF） method with the Finite Volume Method （FVM） was used to simulate the water-air two-phase flow to examine the computed area. On the basis of the ecological-hydraulic characteristics of Chinese sturgeon, the features of the flow field were investigated to provide theoretical support for the proper management of the Three Gorges Reservoir.
