Sharples’ 1 D physical model employing tide wind driven turbulence closure and surface heating cooling physics, was coupled with an ecological model with 9 biochemical components: phytoplankton, zooplankton, shellfis...Sharples’ 1 D physical model employing tide wind driven turbulence closure and surface heating cooling physics, was coupled with an ecological model with 9 biochemical components: phytoplankton, zooplankton, shellfish, autotrophic and heterotrophic bacterioplankton, dissolved organic carbon (DOC), suspended detritus and sinking particles to simulate the annual evolution of ecosystem in the central part of Jiaozhou Bay. The coupled modeling results showed that the phytoplankton shading effect could reduce seawater temperature by 2℃, so that photosynthesis efficiency should be less than 8%; that the loss of phytoplankton by zooplankton grazing in winter tended to be compensated by phytoplankton advection and diffusion from the outside of the Bay; that the incident irradiance intensity could be the most important factor for phytoplankton growth rate; and that it was the bacterial secondary production that maintained the maximum zooplankton biomass in winter usually observed in the 1990s, indicating that the microbial food loop was extremely important for ecosystem study of Jiaozhou Bay.展开更多
The hydraulic system is the key component in the widely used wave energy converters(WEC).In this paper,we theoretically analyze and describe our investigation of the efficiency of the hydraulic system by simulation an...The hydraulic system is the key component in the widely used wave energy converters(WEC).In this paper,we theoretically analyze and describe our investigation of the efficiency of the hydraulic system by simulation and model testing of the combined heaving-buoy WEC.We derive a new governing equation that includes nonlinear hydraulic resistance in the power take-off(PTO).We conducted a physical model experiment based on a 100-kW prototype and applied a hydraulic system with an energy accumulator.The model test results reveal an important parameter related to efficiency with respect to nonlinear hydraulic resistance.We also studied the relationship between the efficiency and the initial conditions.Finally,based on our numerical simulation results,we discuss the effect on efficiency of the gas content of the hydraulic fluid and ways to reduce its impact.展开更多
CFD models have been developed to investigate the Iongwall goaf gas flow patternsunder different mining and geological control conditions.The Iongwall goaf wastreated as porous regions and gas flow was modelled as a m...CFD models have been developed to investigate the Iongwall goaf gas flow patternsunder different mining and geological control conditions.The Iongwall goaf wastreated as porous regions and gas flow was modelled as a momentum sink added to themomentum equation.Gas desorption from the caved goaf and destressed coal seamswithin the mining disturbed area was modelled as additional mass sources in the continuityequation.These CFD models were developed according to specific Iongwall layoutsand calibrated against field monitoring data.Two case studies were presented demonstratingthe application of CFD modelling of goaf gas flow characteristics for improved goafgas capture and the reduction of oxygen ingress into the goaf areas for self-heating prevention.Results from the case studies indicate that the optimum goaf drainage strategywould be a combination of shallow (near the face) and deep holes to improve the overalldrainage efficiency and gas purity.For gassy Iongwall faces retreating against the seam dip,it is recommended to conduct cross-measure roof hole drainage targeting the fracturedzones overlying the return corner,rather than high capacity surface goaf drainage deep inthe goaf.展开更多
Residence time is an important indicator for river environmental management.In this paper,a 3D hydrodynamic model has been successfully applied to Little Manatee River to characterize the mixing and transport process ...Residence time is an important indicator for river environmental management.In this paper,a 3D hydrodynamic model has been successfully applied to Little Manatee River to characterize the mixing and transport process and residence time.The model employs horizontal curvilinear orthogonal grids to represent the complex river system that consists of branches and bayous.The model has been satisfactorily calibrated and verified by using two continuous data sets.The data sets consist of hourly observations of all forcing boundaries,including freshwater inputs,tides,winds,salinity and temperatures at bay boundary,and air temperatures for model simulations.The data sets also consist of hourly observations of water levels,salinity,and temperature at several river stations.The calibrated and verified hydrodynamic model was used to predict residence time in the Little Manatee River.Under the minimum flow of 0.312 m3/s,the pulse residence time(PRT) is 108 days.Model simulations were also conducted for 17 flow scenarios.Empirical regression equations have been satisfactorily derived to correlate PRT to freshwater inflow.Correlation coefficient R2 is 0.982 for PRT.展开更多
To solve nutrient flux and budget among waters with distinct salinity difference for water-salt- nutrient budget, a traditional method is to build a stoichiometrically linked steady state model. However, the tradition...To solve nutrient flux and budget among waters with distinct salinity difference for water-salt- nutrient budget, a traditional method is to build a stoichiometrically linked steady state model. However, the traditional way cannot cope appropriately with those without distinct salinity difference that parallel to coastline or in a complex current system, as the results would be highly affected by box division in time and space, such as the Changjiang （Yangtze） River estuary （CRE） and adjacent waters （30.75°-31.75°N, 122°10′-123°20′E）. Therefore, we developed a hydrodynamic box model based on the traditional way and the regional oceanic modeling system model （ROMS）. Using data from four cruises in 2005, horizontal, vertical and boundary nutrient fluxes were calculated in the hydrodynamic box model, in which flux fields and the major controlling factors were studied. Results show that the nutrient flux varied greatly in season and space. Water flux outweighs the nutrient concentration in horizontal flux, and upwelling flux outweighs upward diffusion flux in vertical direction （upwelling flux and upward diffusion flux regions overlap largely all the year）. Vertical flux in spring and summer are much greater than that in autumn and winter. The maximum vertical flux for DIP （dissolved inorganic phosphate） occurs in summer. Additional to the fluxes of the ChanNiang River discharge, coastal currents, the Taiwan Warm Current, and the upwelling, nutrient flux inflow from the southern Yellow Sea and outflow southward are found crucial to nutrient budgets of the study area. Horizontal nutrient flux is controlled by physical dilution and confined to coastal waters with a little into the open seas. The study area acts as a conveyer transferring nutrients from the Yellow Sea to the East China Sea in the whole year. In addition, vertical nutrient flux in spring and summer is a main source of DIP. Therefore, the hydrodynamic ROMS-based box model is superior to the traditional one in estimating nutrient fluxes in a complicated hydrodynamic current system and provides a modified box model approach to material flux research.展开更多
This paper put forward the structure and construction process of three-dimensional visualization of hydroelectric construction system model based on GIS and 3D visualization platform. The paper first describes the 3D ...This paper put forward the structure and construction process of three-dimensional visualization of hydroelectric construction system model based on GIS and 3D visualization platform. The paper first describes the 3D visualization based on GIS, then discusses the method of constructing 3D visual digital model, and then introduces the terrain digital technology, feature modeling technology. Finally, the technical route shows that this method has good practicability.展开更多
The Vietnamese Mekong Delta is located at the end of the Mekong River, one of the 10 largest rivers in the world. It plays an important role, especially in terms of food security for not only Vietnam but also the worl...The Vietnamese Mekong Delta is located at the end of the Mekong River, one of the 10 largest rivers in the world. It plays an important role, especially in terms of food security for not only Vietnam but also the world. However, the Vietnamese Mekong Delta is projected to be heavily affected by： （1） the annual （fluvial） flood, which would be changed in terms of time and spatial distribution after impacts of climate change scenarios （i.e., sharper hydrograph with shorter flood period）; and （2） sea level rise. Such combination would result in significant changes of surface water resources, leading to consequent impacts on the existing fanning systems in the Vietnamese Mekong Delta. Therefore, this paper presents a new approach of integrating a one-dimensional hydrodynamic model （ISIS-1 D） with GIS （Geographic Information System ） analyses to： （1） identify priority areas for flood adaptation and mitigation; （2） provide an insight to local decision-makers in the Vietnamese Mekong Delta in changes of future floods.展开更多
The article is an attempt to compile the results of CFD liquid flow simulation through pipeline section containing hydraulic elbow with the results of ultrasonic flow measurements. To carry out the measurements behind...The article is an attempt to compile the results of CFD liquid flow simulation through pipeline section containing hydraulic elbow with the results of ultrasonic flow measurements. To carry out the measurements behind the flow disturbing element(hydraulic elbow), an ultrasonic flowmeter with applied head set in accordance with the Z-type system was used. For comparative purposes, a flow simulation for 3 different turbulence models(k-epsilon, SST and SSG) was performed. It was found that with a proper ultrasonic flowmeter heads configurations, it is possible to measure the flow rate disturbed by the hydraulic elbow at any distance from the source of the disturbance. It has to use appropriate correction factor that can be determined by knowing the flow velocity profile equation. Based on comparison of CFD simulation results with experimental data, the accuracy/purposefulness of using individual turbulence models in the case of discussed hydraulic installation was evaluated.展开更多
文摘Sharples’ 1 D physical model employing tide wind driven turbulence closure and surface heating cooling physics, was coupled with an ecological model with 9 biochemical components: phytoplankton, zooplankton, shellfish, autotrophic and heterotrophic bacterioplankton, dissolved organic carbon (DOC), suspended detritus and sinking particles to simulate the annual evolution of ecosystem in the central part of Jiaozhou Bay. The coupled modeling results showed that the phytoplankton shading effect could reduce seawater temperature by 2℃, so that photosynthesis efficiency should be less than 8%; that the loss of phytoplankton by zooplankton grazing in winter tended to be compensated by phytoplankton advection and diffusion from the outside of the Bay; that the incident irradiance intensity could be the most important factor for phytoplankton growth rate; and that it was the bacterial secondary production that maintained the maximum zooplankton biomass in winter usually observed in the 1990s, indicating that the microbial food loop was extremely important for ecosystem study of Jiaozhou Bay.
基金the support of the Marine Renewable Energy Project(No.GHME2016YY02)the National Natural Science Foundation of China(Nos.41376100 and 41706100)+1 种基金the Shandong Provincial Natural Science Key Basic Program(No.ZR2017ZA0202)the Fundamental Research Funds for the Central Universities(No.201564005)
文摘The hydraulic system is the key component in the widely used wave energy converters(WEC).In this paper,we theoretically analyze and describe our investigation of the efficiency of the hydraulic system by simulation and model testing of the combined heaving-buoy WEC.We derive a new governing equation that includes nonlinear hydraulic resistance in the power take-off(PTO).We conducted a physical model experiment based on a 100-kW prototype and applied a hydraulic system with an energy accumulator.The model test results reveal an important parameter related to efficiency with respect to nonlinear hydraulic resistance.We also studied the relationship between the efficiency and the initial conditions.Finally,based on our numerical simulation results,we discuss the effect on efficiency of the gas content of the hydraulic fluid and ways to reduce its impact.
文摘CFD models have been developed to investigate the Iongwall goaf gas flow patternsunder different mining and geological control conditions.The Iongwall goaf wastreated as porous regions and gas flow was modelled as a momentum sink added to themomentum equation.Gas desorption from the caved goaf and destressed coal seamswithin the mining disturbed area was modelled as additional mass sources in the continuityequation.These CFD models were developed according to specific Iongwall layoutsand calibrated against field monitoring data.Two case studies were presented demonstratingthe application of CFD modelling of goaf gas flow characteristics for improved goafgas capture and the reduction of oxygen ingress into the goaf areas for self-heating prevention.Results from the case studies indicate that the optimum goaf drainage strategywould be a combination of shallow (near the face) and deep holes to improve the overalldrainage efficiency and gas purity.For gassy Iongwall faces retreating against the seam dip,it is recommended to conduct cross-measure roof hole drainage targeting the fracturedzones overlying the return corner,rather than high capacity surface goaf drainage deep inthe goaf.
基金supported by the Southwest Florida Water Management District
文摘Residence time is an important indicator for river environmental management.In this paper,a 3D hydrodynamic model has been successfully applied to Little Manatee River to characterize the mixing and transport process and residence time.The model employs horizontal curvilinear orthogonal grids to represent the complex river system that consists of branches and bayous.The model has been satisfactorily calibrated and verified by using two continuous data sets.The data sets consist of hourly observations of all forcing boundaries,including freshwater inputs,tides,winds,salinity and temperatures at bay boundary,and air temperatures for model simulations.The data sets also consist of hourly observations of water levels,salinity,and temperature at several river stations.The calibrated and verified hydrodynamic model was used to predict residence time in the Little Manatee River.Under the minimum flow of 0.312 m3/s,the pulse residence time(PRT) is 108 days.Model simulations were also conducted for 17 flow scenarios.Empirical regression equations have been satisfactorily derived to correlate PRT to freshwater inflow.Correlation coefficient R2 is 0.982 for PRT.
基金Supported by the National Nature Science Foundation of China(Nos.41121064,41276116)the National Basic Research Program of China(973 Program)(No.2010CB428706)
文摘To solve nutrient flux and budget among waters with distinct salinity difference for water-salt- nutrient budget, a traditional method is to build a stoichiometrically linked steady state model. However, the traditional way cannot cope appropriately with those without distinct salinity difference that parallel to coastline or in a complex current system, as the results would be highly affected by box division in time and space, such as the Changjiang （Yangtze） River estuary （CRE） and adjacent waters （30.75°-31.75°N, 122°10′-123°20′E）. Therefore, we developed a hydrodynamic box model based on the traditional way and the regional oceanic modeling system model （ROMS）. Using data from four cruises in 2005, horizontal, vertical and boundary nutrient fluxes were calculated in the hydrodynamic box model, in which flux fields and the major controlling factors were studied. Results show that the nutrient flux varied greatly in season and space. Water flux outweighs the nutrient concentration in horizontal flux, and upwelling flux outweighs upward diffusion flux in vertical direction （upwelling flux and upward diffusion flux regions overlap largely all the year）. Vertical flux in spring and summer are much greater than that in autumn and winter. The maximum vertical flux for DIP （dissolved inorganic phosphate） occurs in summer. Additional to the fluxes of the ChanNiang River discharge, coastal currents, the Taiwan Warm Current, and the upwelling, nutrient flux inflow from the southern Yellow Sea and outflow southward are found crucial to nutrient budgets of the study area. Horizontal nutrient flux is controlled by physical dilution and confined to coastal waters with a little into the open seas. The study area acts as a conveyer transferring nutrients from the Yellow Sea to the East China Sea in the whole year. In addition, vertical nutrient flux in spring and summer is a main source of DIP. Therefore, the hydrodynamic ROMS-based box model is superior to the traditional one in estimating nutrient fluxes in a complicated hydrodynamic current system and provides a modified box model approach to material flux research.
文摘This paper put forward the structure and construction process of three-dimensional visualization of hydroelectric construction system model based on GIS and 3D visualization platform. The paper first describes the 3D visualization based on GIS, then discusses the method of constructing 3D visual digital model, and then introduces the terrain digital technology, feature modeling technology. Finally, the technical route shows that this method has good practicability.
文摘The Vietnamese Mekong Delta is located at the end of the Mekong River, one of the 10 largest rivers in the world. It plays an important role, especially in terms of food security for not only Vietnam but also the world. However, the Vietnamese Mekong Delta is projected to be heavily affected by： （1） the annual （fluvial） flood, which would be changed in terms of time and spatial distribution after impacts of climate change scenarios （i.e., sharper hydrograph with shorter flood period）; and （2） sea level rise. Such combination would result in significant changes of surface water resources, leading to consequent impacts on the existing fanning systems in the Vietnamese Mekong Delta. Therefore, this paper presents a new approach of integrating a one-dimensional hydrodynamic model （ISIS-1 D） with GIS （Geographic Information System ） analyses to： （1） identify priority areas for flood adaptation and mitigation; （2） provide an insight to local decision-makers in the Vietnamese Mekong Delta in changes of future floods.
文摘The article is an attempt to compile the results of CFD liquid flow simulation through pipeline section containing hydraulic elbow with the results of ultrasonic flow measurements. To carry out the measurements behind the flow disturbing element(hydraulic elbow), an ultrasonic flowmeter with applied head set in accordance with the Z-type system was used. For comparative purposes, a flow simulation for 3 different turbulence models(k-epsilon, SST and SSG) was performed. It was found that with a proper ultrasonic flowmeter heads configurations, it is possible to measure the flow rate disturbed by the hydraulic elbow at any distance from the source of the disturbance. It has to use appropriate correction factor that can be determined by knowing the flow velocity profile equation. Based on comparison of CFD simulation results with experimental data, the accuracy/purposefulness of using individual turbulence models in the case of discussed hydraulic installation was evaluated.
