In order to evaluate the need of controlling the temperature of water discharged from the Fenhe Reservoir, the reservoir water temperature distribution was examined. A three-dimensional mathematical model was used to ...In order to evaluate the need of controlling the temperature of water discharged from the Fenhe Reservoir, the reservoir water temperature distribution was examined. A three-dimensional mathematical model was used to simulate the in-plane and vertical distribution of water temperature. The parameters of the model were calibrated with field data of the temperature distribution in the Fenhe Reservoir. The simulated temperature of discharged water is consistent with the measured data. The difference in temperature between the discharged water and the natural river channel is less than 3 ℃ under the current operating conditions. This will not significantly impact the environment of downstream areas.展开更多
In this paper, the subject of mathematical model is a series of math expressions, which is used to calculate different regions＇ volume fraction and analyze flow characterization in multi-strand tundish. But research ...In this paper, the subject of mathematical model is a series of math expressions, which is used to calculate different regions＇ volume fraction and analyze flow characterization in multi-strand tundish. But research about mathematical model for multi-strand tundish is few, and so far, there has been no acknowledged math model for multi- strand tundish to describe its flow characteristic. If Sahai＇s model, which is originally proposed for the case of single-strand tundish （proposed in reference, and this model is widely used in the world）, is applied to describe flow feature in multi-strand tundish, the calculation results would be unreasonable. Based on the data of watermodel experiment results, the sum of each strand＇s dead region＇s volume fraction is bigger than 100%, and this obviously doesn＇T agree with reality; and the value of dead region＇s volume fraction is calculated to be minus according to mathematical simulation results data in another case. What＇s more, Sahai＇s model does not propose the standard of plotting the RTD-curve, and this makes scholars around the world can＇t achieve consensus of views about plotting RTD-curve. And the model doesn＇t consider the bypass flow and can＇t calculate its volume fraction, but bypass flow is critical to tundish metallurgy. And through Sahai＇s model, the calculation result of plug flow region＇s volume fraction is also not reasonable, because the model doesn＇t well describe the essence of plug flow. So these suggest that it is not reliable to apply Sahai＇s single-strand tundish model to multi-strand tundish case. Then a new model is attempted to propose in this paper for your discussion. In the new model, the standard of plotting RTD curve is definitely proposed, and relative calculation method is also proposed; and the feature of dead region is carefully studied and the model proposes a new method to calculate its volume fraction, and the calculation formula about its volume fraction can be adjustable according the actual demand; what＇s more, the new model considers the bypass flow and proposes a method to calculate its volume fraction for the first time, and then volume fraction of plug flow region, backmix flow region, dead region and bypass flow can be calculated and obtained at the same time; and this new model can better capture the deviation of reality flow pattern from ideal plug flow pattern, and reflects the feature of plug flow.展开更多
This paper studies the modelling and simulation for all forms of hcaters.The assumption of former days that the temperature of condensation is the saturationtemperature corresponding to heater pressure in steam side i...This paper studies the modelling and simulation for all forms of hcaters.The assumption of former days that the temperature of condensation is the saturationtemperature corresponding to heater pressure in steam side is no longer used.On the basisof the laws of conservation of mass,energy and momentum,the mathematical model ofheaters is established and the simulation calculation of a 125MW unit is made.The rcsultshows that the model is applicable for various kinds of steam-water heater in power plant.展开更多
Large scale turbulent structures play an important role in mass transport of natural river turbulence diffusion, After adopting the theory of Large Scale Turbulent Simulation to natural rivers, some 1-D stream quality...Large scale turbulent structures play an important role in mass transport of natural river turbulence diffusion, After adopting the theory of Large Scale Turbulent Simulation to natural rivers, some 1-D stream quality models, such as QUAL-II, have been widely applied to large, middle and small rivers in China with reasonable success. Moreover, on this basis, 2-D and 3-D river quality models have also been developed. Both 2-D and 3-D models used upwind scheme plus Peaceman-Rachford's alternating scheme in the first one and Douglas' scheme in the second one. These models have also been successfully applied to the Yangtze River as well as some middle and small rivers in China.展开更多
River-type reservoir is narrow and long in shape and has many reservoir bends and confluence of tributaries. On the basis of Saint-Venant equation and differential equation for longitudinal diffusion and in considerat...River-type reservoir is narrow and long in shape and has many reservoir bends and confluence of tributaries. On the basis of Saint-Venant equation and differential equation for longitudinal diffusion and in consideration of the influence of confluences and bends, in order to predict the water quantity and quality, an one-dimensional unsteady mathematical model was established in this paper. The model consists of a hydrodynamic model and a water quality model. The average hydraulic characteristics and water quality parameters were calculated for a reservoir with two confluences and four bends. Computed results are in good agreement with field observation data. The model can be applied to predict the water quantity, water level and water quality of the river-type reservoirs.展开更多
Aerated jets, such as the jet flow behind the flip bucket of an overflow dam, widely exists in hydraulic engineering. Up to now the model test and prototype observation have been two main methods of studying the aerat...Aerated jets, such as the jet flow behind the flip bucket of an overflow dam, widely exists in hydraulic engineering. Up to now the model test and prototype observation have been two main methods of studying the aerated jet for a special hydraulic project. A three-dimensional mathematical model for the aerated jet was established. It seems that the suggested model has high predictive power in comparison with the original two methods of model test and prototype observation which is very useful in the study of energy dissipation and jet flow atomization.展开更多
Based on a 3-D dynamic numerical model of primitive equation, the general circulation in the East China Sea and the Yellow Sea was studied with a 0.25 ° ×0.25 ° horizontal grid and a realistic bottom to...Based on a 3-D dynamic numerical model of primitive equation, the general circulation in the East China Sea and the Yellow Sea was studied with a 0.25 ° ×0.25 ° horizontal grid and a realistic bottom topography. The tidal current and Kuroshio (Japan current) were considered. The main results of the general circulation in the East China Sea and the Yellow Sea were obtained. The numerical results were compared with the observed results. The compared results show that 3-D dynamic numerical model is efficient to predict general circulation in the East China Sea and the Yellow Sea.展开更多
In this paper, we investigate the selection rule for desalinating seawater using functionalized graphene sheet as a semi-permissible membrane. Both the applied mathematical modeling and MD simulations will be used to ...In this paper, we investigate the selection rule for desalinating seawater using functionalized graphene sheet as a semi-permissible membrane. Both the applied mathematical modeling and MD simulations will be used to determine the acceptance conditions for water molecule or sodium ion permeating into the functionalized graphene. Both the Lennard-Jones potential and Coulomb forces are considered by taking into accounts the major molecular and ionic interactions between molecules, ions and functionalized graphene sheet. The continuous approximation will then be used to coarse grain most significant molecular and ionic interactions so that the multi-body problems could be simplified into several two-body problems and the 3D motions are reduced into degenerated 1D motion. Our mathematical model and simulations show that the negatively charged graphene always accepts sodium ions and water;however the permeability of water molecules and sodium ions becomes very sensitive to the presence of positive charges on the graphene.展开更多
文摘In order to evaluate the need of controlling the temperature of water discharged from the Fenhe Reservoir, the reservoir water temperature distribution was examined. A three-dimensional mathematical model was used to simulate the in-plane and vertical distribution of water temperature. The parameters of the model were calibrated with field data of the temperature distribution in the Fenhe Reservoir. The simulated temperature of discharged water is consistent with the measured data. The difference in temperature between the discharged water and the natural river channel is less than 3 ℃ under the current operating conditions. This will not significantly impact the environment of downstream areas.
基金supported by the National Natural Science Foundation of China(No.60672145)
文摘In this paper, the subject of mathematical model is a series of math expressions, which is used to calculate different regions＇ volume fraction and analyze flow characterization in multi-strand tundish. But research about mathematical model for multi-strand tundish is few, and so far, there has been no acknowledged math model for multi- strand tundish to describe its flow characteristic. If Sahai＇s model, which is originally proposed for the case of single-strand tundish （proposed in reference, and this model is widely used in the world）, is applied to describe flow feature in multi-strand tundish, the calculation results would be unreasonable. Based on the data of watermodel experiment results, the sum of each strand＇s dead region＇s volume fraction is bigger than 100%, and this obviously doesn＇T agree with reality; and the value of dead region＇s volume fraction is calculated to be minus according to mathematical simulation results data in another case. What＇s more, Sahai＇s model does not propose the standard of plotting the RTD-curve, and this makes scholars around the world can＇t achieve consensus of views about plotting RTD-curve. And the model doesn＇t consider the bypass flow and can＇t calculate its volume fraction, but bypass flow is critical to tundish metallurgy. And through Sahai＇s model, the calculation result of plug flow region＇s volume fraction is also not reasonable, because the model doesn＇t well describe the essence of plug flow. So these suggest that it is not reliable to apply Sahai＇s single-strand tundish model to multi-strand tundish case. Then a new model is attempted to propose in this paper for your discussion. In the new model, the standard of plotting RTD curve is definitely proposed, and relative calculation method is also proposed; and the feature of dead region is carefully studied and the model proposes a new method to calculate its volume fraction, and the calculation formula about its volume fraction can be adjustable according the actual demand; what＇s more, the new model considers the bypass flow and proposes a method to calculate its volume fraction for the first time, and then volume fraction of plug flow region, backmix flow region, dead region and bypass flow can be calculated and obtained at the same time; and this new model can better capture the deviation of reality flow pattern from ideal plug flow pattern, and reflects the feature of plug flow.
文摘This paper studies the modelling and simulation for all forms of hcaters.The assumption of former days that the temperature of condensation is the saturationtemperature corresponding to heater pressure in steam side is no longer used.On the basisof the laws of conservation of mass,energy and momentum,the mathematical model ofheaters is established and the simulation calculation of a 125MW unit is made.The rcsultshows that the model is applicable for various kinds of steam-water heater in power plant.
文摘Large scale turbulent structures play an important role in mass transport of natural river turbulence diffusion, After adopting the theory of Large Scale Turbulent Simulation to natural rivers, some 1-D stream quality models, such as QUAL-II, have been widely applied to large, middle and small rivers in China with reasonable success. Moreover, on this basis, 2-D and 3-D river quality models have also been developed. Both 2-D and 3-D models used upwind scheme plus Peaceman-Rachford's alternating scheme in the first one and Douglas' scheme in the second one. These models have also been successfully applied to the Yangtze River as well as some middle and small rivers in China.
文摘River-type reservoir is narrow and long in shape and has many reservoir bends and confluence of tributaries. On the basis of Saint-Venant equation and differential equation for longitudinal diffusion and in consideration of the influence of confluences and bends, in order to predict the water quantity and quality, an one-dimensional unsteady mathematical model was established in this paper. The model consists of a hydrodynamic model and a water quality model. The average hydraulic characteristics and water quality parameters were calculated for a reservoir with two confluences and four bends. Computed results are in good agreement with field observation data. The model can be applied to predict the water quantity, water level and water quality of the river-type reservoirs.
文摘Aerated jets, such as the jet flow behind the flip bucket of an overflow dam, widely exists in hydraulic engineering. Up to now the model test and prototype observation have been two main methods of studying the aerated jet for a special hydraulic project. A three-dimensional mathematical model for the aerated jet was established. It seems that the suggested model has high predictive power in comparison with the original two methods of model test and prototype observation which is very useful in the study of energy dissipation and jet flow atomization.
文摘Based on a 3-D dynamic numerical model of primitive equation, the general circulation in the East China Sea and the Yellow Sea was studied with a 0.25 ° ×0.25 ° horizontal grid and a realistic bottom topography. The tidal current and Kuroshio (Japan current) were considered. The main results of the general circulation in the East China Sea and the Yellow Sea were obtained. The numerical results were compared with the observed results. The compared results show that 3-D dynamic numerical model is efficient to predict general circulation in the East China Sea and the Yellow Sea.
文摘In this paper, we investigate the selection rule for desalinating seawater using functionalized graphene sheet as a semi-permissible membrane. Both the applied mathematical modeling and MD simulations will be used to determine the acceptance conditions for water molecule or sodium ion permeating into the functionalized graphene. Both the Lennard-Jones potential and Coulomb forces are considered by taking into accounts the major molecular and ionic interactions between molecules, ions and functionalized graphene sheet. The continuous approximation will then be used to coarse grain most significant molecular and ionic interactions so that the multi-body problems could be simplified into several two-body problems and the 3D motions are reduced into degenerated 1D motion. Our mathematical model and simulations show that the negatively charged graphene always accepts sodium ions and water;however the permeability of water molecules and sodium ions becomes very sensitive to the presence of positive charges on the graphene.
