In the paper a new two-dimensional 'man-WCV'(water cooling vest) mathematical model is developed. This model is of practical use: it can predict transient temperature responses and body temperature distributio...In the paper a new two-dimensional 'man-WCV'(water cooling vest) mathematical model is developed. This model is of practical use: it can predict transient temperature responses and body temperature distribution for a person in a nonuniform hot environment, doing various jobs and dressed in different clothes. In addition, the results calculated from the model can be used to optimize the distribution of the tube-net lined on the WCV and to evaluate an individual thermal conditioning system with cooling water. The results obtained from the model agree well with the author's experimental data.展开更多
Generally, in the literature, the hydrodynamic behavior of an EGSB （expanded granular sludge bed） reactor is considered as a complete mix reactor. Few works study in detail the flow of such reactors. The aim of this...Generally, in the literature, the hydrodynamic behavior of an EGSB （expanded granular sludge bed） reactor is considered as a complete mix reactor. Few works study in detail the flow of such reactors. The aim of this work was to study, in detail, the hydrodynamics of an EGSB reactor and to propose a mathematical model to describe its flow. A 3.04 L reactor was used with HRT （hydraulic retention time） of 12 h, affluent flowrate of 4 mL·min^-1, and the recirculation flow rate was changed to study three different upflow velocities in the tube （6, 8 and 10 m·h^-1. The pulse input method was used, with the use of blue dextran as tracer. In order to consider the dimensional differences between the tube and the separator, the reactor was divided into two regions （tube and separator）. Initially, a model with two tubular reactors with dispersion in series was proposed and the Peclet number was adjusted for the two regions. It was observed that the region of the tube shows the behavior of a tubular reactor with high dispersion, whereas the region of the separator shows the behavior of a complete mix reactor. In order to simplify the equation, and by knowing that the concentration profile along the reactor was almost constant, a model of two CSTRs （continuous stirred tank reactors） was proposed in series and the number of reactors （N） was set. The best combination was five CSTRs, three in the tube region and two in the separator region. The presented models were equivalent and can be used to describe the hydrodynamic behavior of the EGSB reactor.展开更多
Based on the combined hydraulic calculation for the eastern network region at the Pearl River estuary and several outlets to the Lingdingyang Bay, the sediment calculation modelling was introduced in the establishment...Based on the combined hydraulic calculation for the eastern network region at the Pearl River estuary and several outlets to the Lingdingyang Bay, the sediment calculation modelling was introduced in the establishment of the sediment mathematical model for Lingdingyang Bay and the eastern region with one and two dimensional flow calculation. Model adjustment and verification were performed in conjunction with field data. The simulated results coincide well with measured data.In addition the model is applied to predict the shore-line planning scheme of Lingdingyang Bay.The theoretical criterion is provided for the shore line plan in the model.And a new mathematical simulated method is put out to research the planning engineering concerned with one-dimensional net rivers and two-dimensional estuary.展开更多
The method of combining a physical model with a mathematical model is described to study the concentration profile of pollutant dispersion in the Yangtze Estuary. the Experiments are described regarding a jet in a tid...The method of combining a physical model with a mathematical model is described to study the concentration profile of pollutant dispersion in the Yangtze Estuary. the Experiments are described regarding a jet in a tidal physical model and two-dimensional calculations of diffusion using momentum and mass conservation equations of unsteady flow. The feature of dispersion in the tidal flow, which is different from that in the steady flow such as rivers, is explained. Dilution and dispersion mainly depend on the volume of runoff and tidal range. The results of the measurement and calculation are presented, and it can be seen that they are in good agreement.展开更多
A two-dimensional computational model is develope for the calulation of tides, storm surges and otherlong-period waves in coastal and shelf waters. The Partial differental equations are approximated by two sets of dif...A two-dimensional computational model is develope for the calulation of tides, storm surges and otherlong-period waves in coastal and shelf waters. The Partial differental equations are approximated by two sets of difference equations on a space-staggered grid system. Both sets are explicit with one set for water level and x-component velocity, and another for water level and y-component velocity. These two sets are used successively for stepby-step solution in time. An analytical investigation on the linearized sets of the difference equations indicates that thecomputational scheme is unconditionally stable. The model is of second order accuracy both in space and in time andconserves mass and momentum. Simulations of surface elevation caused by periodic forcing in one-opening rectangularbasin with flat topography and by steady wind stress in the basin with flat or slope topography show that the computed results are in excellent agreement with the corresponding analytic solutions. The steady-tate wind-induced setupin a ofed basin with discontinuous topography computed with the present model are also in excellent agreement withthe results from Leendertse's model. Finally, the model is applied to hindcast a storm surge in the South China Seaand reproduces the surge elevation satisfactorily.展开更多
As is known, the Great Red Spot (GRS) is one of the most mysterious sights in the solar system and is a strong storm that is quite large. According to the laws of hydrodynamics and gas dynamics, it should have disappe...As is known, the Great Red Spot (GRS) is one of the most mysterious sights in the solar system and is a strong storm that is quite large. According to the laws of hydrodynamics and gas dynamics, it should have disappeared several centuries ago, but scientists still observe it and cannot accurately explain this phenomenon. Since turbulence and atmospheric waves in the GRS region absorb the energy of its winds, the vortex loses energy by radiating heat. In the work, it is proved with a mathematical and non-classical approach that the GRS and anticyclones will live for a long time;otherwise, we had to first of all prove that the vortex threads (loops) and ovals could not exist. Based on these supports, mathematical methods prove their existence forever by observing a large vortex (GRS);moreover, they are sources of heat. When proofs are obtained, the results are consistent with the previous hypotheses of the researcher. The introduction of the work gives a comparison of various hypotheses;for example, one of them states that the decrease in the size of the GRS is only an illusory observation. Next, we first consider the applicability conditions for the mathematical justification of the hypothesis of the longevity of the Great Red Spot. The wind equation and the GRS are energized by absorbing smaller eddies and ovals, and this total energy is constant. With the help of the KH mechanism in the case of Brunt Vaisala, the frequencies (which can be calculated by a program with given formulas) are determined using very strictly mathematical evidence to substantiate the validity of the hypothesis about the longevity of Jupiter’s Great Red Spot.展开更多
A two-dimensional mathematical model was built to describe the melting process of cylindrical basalt particle bed in a crucible. The melting processes with respect to the factors of thermal boundary conditions and par...A two-dimensional mathematical model was built to describe the melting process of cylindrical basalt particle bed in a crucible. The melting processes with respect to the factors of thermal boundary conditions and particle sizes of basalt were simulated by using the numerical method (FDM). The governing equations were discretized in tridiagonal matrix form and were solved by using the tridiagonal matrix algorithm (TDMA) as well as the alternative direction implicit (ADI) solver. The temperature distribution, the moving law of the two dimensional phase-change boundaries, the thermal current distribution were given through the numerical simulation. The results provided a theoretical basis for deciding heating procedure, for evaluating power import and controlling furnace temperature and for predicting basalt melting states etc. In the experiment, an electrical furnace was designed based on the computations. It has been proved that the simulation results are reasonably coincident with the experimental data.展开更多
Cocurrent gas-solid downer reactors have many applications in industry because they possess the tech- nological advantages of a lower pressure drop, shorter residence time, and less solid backmixing when compared with...Cocurrent gas-solid downer reactors have many applications in industry because they possess the tech- nological advantages of a lower pressure drop, shorter residence time, and less solid backmixing when compared with traditional circulating fluidized bed risers. By introducing the concept of particle clusters explicitly, a one-dimensional model with consideration of the interphase interactions between the fluid and particles at both microscale and mesoscale is formulated for concurrent downward gas-solid flow according to energy-minimization multi-scale （EMMS） theory. A unified stability condition is proposed for the differently developed sections of gas-solid flow according to the principle of the compromise in competition between dominant mechanisms. By optimizing the number density of particle clusters with respect to the stability condition, the formulated model can be numerically solved without introducing cluster-specific empirical correlations. The EMMS-based model predicts well the axial hydrodynamics of cocurrent gas-solid downers and is expected to have a wider range of applications than the existing cluster-based models.展开更多
The paper discusses a mathematic model of the Weis-Fogh hydrofoil under the flow upstream with a separation vortex. The analysis makes use of a single-vortex model. We establish the motion equation of the vortex and t...The paper discusses a mathematic model of the Weis-Fogh hydrofoil under the flow upstream with a separation vortex. The analysis makes use of a single-vortex model. We establish the motion equation of the vortex and the initial condition. Applying the complex function theory, we also obtain the analytic formula of the hydrodynamic integrations'which have the complex parameter and the singularity POint. The numeric results compare well with experiment.展开更多
A CFD simulation was proposed to investigate the electrostatic effect on the hydrodynamic behavior of turbulent gas-solid flow in FCC risers. The simulation was first verified using the open experimental data with exp...A CFD simulation was proposed to investigate the electrostatic effect on the hydrodynamic behavior of turbulent gas-solid flow in FCC risers. The simulation was first verified using the open experimental data with expected electrostatic effects observed in FCC risers. The influences of several operating parameters on the degree of electrification in FCC risers were analyzed, such as surface charge densities, pressure, gas velocity. It was noted that the gas velocity played a highly significant role compared with solid flux, while the effect of pressure was relatively weak. Further analysis showed that a much stronger electrostatic effect was found in small-scale FCC risers than their large-scale counterparts, and in addition, the major regions affected by the electrostatic charge depend on the scale of the riser. Finally, an external electric field was applied to optimize the flow field distribution in the FCC riser. The results of the electrostatic effects on the hydrodynamic behaviors in FCC risers are of great use in providing a reference for the optimization of FCC risers and their scaling.展开更多
文摘In the paper a new two-dimensional 'man-WCV'(water cooling vest) mathematical model is developed. This model is of practical use: it can predict transient temperature responses and body temperature distribution for a person in a nonuniform hot environment, doing various jobs and dressed in different clothes. In addition, the results calculated from the model can be used to optimize the distribution of the tube-net lined on the WCV and to evaluate an individual thermal conditioning system with cooling water. The results obtained from the model agree well with the author's experimental data.
文摘Generally, in the literature, the hydrodynamic behavior of an EGSB （expanded granular sludge bed） reactor is considered as a complete mix reactor. Few works study in detail the flow of such reactors. The aim of this work was to study, in detail, the hydrodynamics of an EGSB reactor and to propose a mathematical model to describe its flow. A 3.04 L reactor was used with HRT （hydraulic retention time） of 12 h, affluent flowrate of 4 mL·min^-1, and the recirculation flow rate was changed to study three different upflow velocities in the tube （6, 8 and 10 m·h^-1. The pulse input method was used, with the use of blue dextran as tracer. In order to consider the dimensional differences between the tube and the separator, the reactor was divided into two regions （tube and separator）. Initially, a model with two tubular reactors with dispersion in series was proposed and the Peclet number was adjusted for the two regions. It was observed that the region of the tube shows the behavior of a tubular reactor with high dispersion, whereas the region of the separator shows the behavior of a complete mix reactor. In order to simplify the equation, and by knowing that the concentration profile along the reactor was almost constant, a model of two CSTRs （continuous stirred tank reactors） was proposed in series and the number of reactors （N） was set. The best combination was five CSTRs, three in the tube region and two in the separator region. The presented models were equivalent and can be used to describe the hydrodynamic behavior of the EGSB reactor.
文摘Based on the combined hydraulic calculation for the eastern network region at the Pearl River estuary and several outlets to the Lingdingyang Bay, the sediment calculation modelling was introduced in the establishment of the sediment mathematical model for Lingdingyang Bay and the eastern region with one and two dimensional flow calculation. Model adjustment and verification were performed in conjunction with field data. The simulated results coincide well with measured data.In addition the model is applied to predict the shore-line planning scheme of Lingdingyang Bay.The theoretical criterion is provided for the shore line plan in the model.And a new mathematical simulated method is put out to research the planning engineering concerned with one-dimensional net rivers and two-dimensional estuary.
文摘The method of combining a physical model with a mathematical model is described to study the concentration profile of pollutant dispersion in the Yangtze Estuary. the Experiments are described regarding a jet in a tidal physical model and two-dimensional calculations of diffusion using momentum and mass conservation equations of unsteady flow. The feature of dispersion in the tidal flow, which is different from that in the steady flow such as rivers, is explained. Dilution and dispersion mainly depend on the volume of runoff and tidal range. The results of the measurement and calculation are presented, and it can be seen that they are in good agreement.
文摘A two-dimensional computational model is develope for the calulation of tides, storm surges and otherlong-period waves in coastal and shelf waters. The Partial differental equations are approximated by two sets of difference equations on a space-staggered grid system. Both sets are explicit with one set for water level and x-component velocity, and another for water level and y-component velocity. These two sets are used successively for stepby-step solution in time. An analytical investigation on the linearized sets of the difference equations indicates that thecomputational scheme is unconditionally stable. The model is of second order accuracy both in space and in time andconserves mass and momentum. Simulations of surface elevation caused by periodic forcing in one-opening rectangularbasin with flat topography and by steady wind stress in the basin with flat or slope topography show that the computed results are in excellent agreement with the corresponding analytic solutions. The steady-tate wind-induced setupin a ofed basin with discontinuous topography computed with the present model are also in excellent agreement withthe results from Leendertse's model. Finally, the model is applied to hindcast a storm surge in the South China Seaand reproduces the surge elevation satisfactorily.
文摘As is known, the Great Red Spot (GRS) is one of the most mysterious sights in the solar system and is a strong storm that is quite large. According to the laws of hydrodynamics and gas dynamics, it should have disappeared several centuries ago, but scientists still observe it and cannot accurately explain this phenomenon. Since turbulence and atmospheric waves in the GRS region absorb the energy of its winds, the vortex loses energy by radiating heat. In the work, it is proved with a mathematical and non-classical approach that the GRS and anticyclones will live for a long time;otherwise, we had to first of all prove that the vortex threads (loops) and ovals could not exist. Based on these supports, mathematical methods prove their existence forever by observing a large vortex (GRS);moreover, they are sources of heat. When proofs are obtained, the results are consistent with the previous hypotheses of the researcher. The introduction of the work gives a comparison of various hypotheses;for example, one of them states that the decrease in the size of the GRS is only an illusory observation. Next, we first consider the applicability conditions for the mathematical justification of the hypothesis of the longevity of the Great Red Spot. The wind equation and the GRS are energized by absorbing smaller eddies and ovals, and this total energy is constant. With the help of the KH mechanism in the case of Brunt Vaisala, the frequencies (which can be calculated by a program with given formulas) are determined using very strictly mathematical evidence to substantiate the validity of the hypothesis about the longevity of Jupiter’s Great Red Spot.
文摘A two-dimensional mathematical model was built to describe the melting process of cylindrical basalt particle bed in a crucible. The melting processes with respect to the factors of thermal boundary conditions and particle sizes of basalt were simulated by using the numerical method (FDM). The governing equations were discretized in tridiagonal matrix form and were solved by using the tridiagonal matrix algorithm (TDMA) as well as the alternative direction implicit (ADI) solver. The temperature distribution, the moving law of the two dimensional phase-change boundaries, the thermal current distribution were given through the numerical simulation. The results provided a theoretical basis for deciding heating procedure, for evaluating power import and controlling furnace temperature and for predicting basalt melting states etc. In the experiment, an electrical furnace was designed based on the computations. It has been proved that the simulation results are reasonably coincident with the experimental data.
基金We appreciate financial support from the Strategic Prior- ity Research Program of the Chinese Academy of Sciences （No. XDA07080400） and the Natural Science Foundation of China （Nos. 21376244 and 91334107）.
文摘Cocurrent gas-solid downer reactors have many applications in industry because they possess the tech- nological advantages of a lower pressure drop, shorter residence time, and less solid backmixing when compared with traditional circulating fluidized bed risers. By introducing the concept of particle clusters explicitly, a one-dimensional model with consideration of the interphase interactions between the fluid and particles at both microscale and mesoscale is formulated for concurrent downward gas-solid flow according to energy-minimization multi-scale （EMMS） theory. A unified stability condition is proposed for the differently developed sections of gas-solid flow according to the principle of the compromise in competition between dominant mechanisms. By optimizing the number density of particle clusters with respect to the stability condition, the formulated model can be numerically solved without introducing cluster-specific empirical correlations. The EMMS-based model predicts well the axial hydrodynamics of cocurrent gas-solid downers and is expected to have a wider range of applications than the existing cluster-based models.
文摘The paper discusses a mathematic model of the Weis-Fogh hydrofoil under the flow upstream with a separation vortex. The analysis makes use of a single-vortex model. We establish the motion equation of the vortex and the initial condition. Applying the complex function theory, we also obtain the analytic formula of the hydrodynamic integrations'which have the complex parameter and the singularity POint. The numeric results compare well with experiment.
基金The authors thank the National Ministry of Science and Tech- nology of China （No. 2012CB21500402）, the National Natural Science Foundation of China （No. U1462101）, the State Key Laboratory of Coal Conversion of China （No. J13-14-102） and the Research Fund for the Doctoral Program of Higher Education （No. 20130073110077） for supporting this work.
文摘A CFD simulation was proposed to investigate the electrostatic effect on the hydrodynamic behavior of turbulent gas-solid flow in FCC risers. The simulation was first verified using the open experimental data with expected electrostatic effects observed in FCC risers. The influences of several operating parameters on the degree of electrification in FCC risers were analyzed, such as surface charge densities, pressure, gas velocity. It was noted that the gas velocity played a highly significant role compared with solid flux, while the effect of pressure was relatively weak. Further analysis showed that a much stronger electrostatic effect was found in small-scale FCC risers than their large-scale counterparts, and in addition, the major regions affected by the electrostatic charge depend on the scale of the riser. Finally, an external electric field was applied to optimize the flow field distribution in the FCC riser. The results of the electrostatic effects on the hydrodynamic behaviors in FCC risers are of great use in providing a reference for the optimization of FCC risers and their scaling.
