In this paper, on the basis of experimental data of two kinds of chemical explosions, the piston-pushing model of spherical blast-waves and the second-order Godunov-type scheme of finite difference methods with high i...In this paper, on the basis of experimental data of two kinds of chemical explosions, the piston-pushing model of spherical blast-waves and the second-order Godunov-type scheme of finite difference methods with high identification to discontinuity are used to the numerical reconstruction of part of an actual hemispherical blast-wave flow field by properly adjusting the moving bounary conditions of a piston. This method is simple and reliable. It is suitable to the evaluation of effects of the blast-wave flow field away from the explosion center.展开更多
The present study aims to improve the efficiency of typical procedures used for post-processing flow field data by applying a neural-network technology.Assuming a problem of aircraft design as the workhorse,a regressi...The present study aims to improve the efficiency of typical procedures used for post-processing flow field data by applying a neural-network technology.Assuming a problem of aircraft design as the workhorse,a regression calculation model for processing the flow data of a FCN-VGG19 aircraft is elaborated based on VGGNet(Visual Geometry Group Net)and FCN(Fully Convolutional Network)techniques.As shown by the results,the model displays a strong fitting ability,and there is almost no over-fitting in training.Moreover,the model has good accuracy and convergence.For different input data and different grids,the model basically achieves convergence,showing good performances.It is shown that the proposed simulation regression model based on FCN has great potential in typical problems of computational fluid dynamics(CFD)and related data processing.展开更多
The formation of mesoscale eddies and the structure of the surface flow field in the Luzon Strait area were examined using in-situ CTD data,Argo float data,and multi-satellite remote sensing data collected from May to...The formation of mesoscale eddies and the structure of the surface flow field in the Luzon Strait area were examined using in-situ CTD data,Argo float data,and multi-satellite remote sensing data collected from May to August 2009. The results show that vigorous water exchange between Kuroshio water and South China Sea(SCS) water began to emerge over the 200 m water column throughout the strait. Based on an objective definition of surface currents,float A69 tracked an anti-cyclonic eddy southwest of Taiwan Island under a Lagrangian current measurement. The salinity inside the anti-cyclonic eddy was higher than in typical SCS water but lower than in Kuroshio mainstream water,indicating that this eddy was induced by Kuroshio frontal intrusion through the Luzon Strait and into the SCS. From hydrographic data,we propose that continuous horizontal diffusion with high-salinity characteristics in the subsurface layer could extend to 119°E or even further west. The high-temperature filament,large positive sea level anomaly and clockwise geostrophic current all confirmed the existence of this warm eddy in May and June. A strongly negative wind stress curl maintained the eddy until it died. The surface flow field during July and August was rather complicated. Float A83 described an east-west orientated shuttle run in the 20°N section that was not reported by previous studies. At the same time,float A80 indicated a Kuroshio bend into the north-central region of Luzon Strait but it did not cross 120.5°E. The water mass rejoining the Kuroshio mainstream from the southern tip of Taiwan Island was less saline,indicating an entrainment of water from SCS by the Kuroshio bend.展开更多
Line integral convolution(LIC)is a useful visualization technique for a vector field.However,the output image produced by LIC has many problems in a marine vector field.We focus on the visual quality improvement when ...Line integral convolution(LIC)is a useful visualization technique for a vector field.However,the output image produced by LIC has many problems in a marine vector field.We focus on the visual quality improvement when LIC is applied in the ocean steady and unsteady flow field in the following aspects.When a white noise is used as the input in a steady flow field,interpolation is used to turn the discrete white noise into continuous white noise to solve the problem of discontinuity.The"cross"high-pass filtering is used to enhance the textures of streamlines to be more concentrated and continuity strengthened for each streamline.When a sparse noise is used as the input in a steady flow field,we change the directions of background sparse noise according to the directions of vector field to make the streamlines clearer and brighter.In addition,we provide a random initial phase for every streamline to avoid the pulsation effect during animation.The velocities of vector field are encoded in the speed of the same length streamlines so that the running speed of streamlines can express flow rate.Meanwhile,to solve the problem of obvious boundaries when stitching image,we change the streamline tracking constraints.When a white noise is used as an input in an unsteady flow field,double value scattering is used to enhance the contrast of streamlines;moreover,the"cross"high-pass filtering is also adopt instead of two-dimensional high-pass filtering.Finally,we apply the above methods to a case of the surface wave field in typhoon condition.Our experimental results show that applying the methods can generate high-quality wave images and animations.Therefore,it is helpful to understand and study waves in typhoon condition to avoid the potential harm of the waves to people's lives and property.展开更多
文摘In this paper, on the basis of experimental data of two kinds of chemical explosions, the piston-pushing model of spherical blast-waves and the second-order Godunov-type scheme of finite difference methods with high identification to discontinuity are used to the numerical reconstruction of part of an actual hemispherical blast-wave flow field by properly adjusting the moving bounary conditions of a piston. This method is simple and reliable. It is suitable to the evaluation of effects of the blast-wave flow field away from the explosion center.
文摘The present study aims to improve the efficiency of typical procedures used for post-processing flow field data by applying a neural-network technology.Assuming a problem of aircraft design as the workhorse,a regression calculation model for processing the flow data of a FCN-VGG19 aircraft is elaborated based on VGGNet(Visual Geometry Group Net)and FCN(Fully Convolutional Network)techniques.As shown by the results,the model displays a strong fitting ability,and there is almost no over-fitting in training.Moreover,the model has good accuracy and convergence.For different input data and different grids,the model basically achieves convergence,showing good performances.It is shown that the proposed simulation regression model based on FCN has great potential in typical problems of computational fluid dynamics(CFD)and related data processing.
基金Supported by the National Natural Science Foundation of China(Nos.41306019,U1133001)the open grant of LTO SCSIO/CAS(No.LTO201305)+4 种基金the Sanya and CAS Cooperation Project(No.2013YD77)the NSFC Innovative Group(No.41421005)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406401)the Pilot Strategic Project of CAS(No.XDA11020101)the Knowledge Innovation Engineering Frontier Project of SIDSSE(No.SIDSSE-201205)
文摘The formation of mesoscale eddies and the structure of the surface flow field in the Luzon Strait area were examined using in-situ CTD data,Argo float data,and multi-satellite remote sensing data collected from May to August 2009. The results show that vigorous water exchange between Kuroshio water and South China Sea(SCS) water began to emerge over the 200 m water column throughout the strait. Based on an objective definition of surface currents,float A69 tracked an anti-cyclonic eddy southwest of Taiwan Island under a Lagrangian current measurement. The salinity inside the anti-cyclonic eddy was higher than in typical SCS water but lower than in Kuroshio mainstream water,indicating that this eddy was induced by Kuroshio frontal intrusion through the Luzon Strait and into the SCS. From hydrographic data,we propose that continuous horizontal diffusion with high-salinity characteristics in the subsurface layer could extend to 119°E or even further west. The high-temperature filament,large positive sea level anomaly and clockwise geostrophic current all confirmed the existence of this warm eddy in May and June. A strongly negative wind stress curl maintained the eddy until it died. The surface flow field during July and August was rather complicated. Float A83 described an east-west orientated shuttle run in the 20°N section that was not reported by previous studies. At the same time,float A80 indicated a Kuroshio bend into the north-central region of Luzon Strait but it did not cross 120.5°E. The water mass rejoining the Kuroshio mainstream from the southern tip of Taiwan Island was less saline,indicating an entrainment of water from SCS by the Kuroshio bend.
基金Supported by the National Key Research and Development Program of China(No.2016YFC1402000)
文摘Line integral convolution(LIC)is a useful visualization technique for a vector field.However,the output image produced by LIC has many problems in a marine vector field.We focus on the visual quality improvement when LIC is applied in the ocean steady and unsteady flow field in the following aspects.When a white noise is used as the input in a steady flow field,interpolation is used to turn the discrete white noise into continuous white noise to solve the problem of discontinuity.The"cross"high-pass filtering is used to enhance the textures of streamlines to be more concentrated and continuity strengthened for each streamline.When a sparse noise is used as the input in a steady flow field,we change the directions of background sparse noise according to the directions of vector field to make the streamlines clearer and brighter.In addition,we provide a random initial phase for every streamline to avoid the pulsation effect during animation.The velocities of vector field are encoded in the speed of the same length streamlines so that the running speed of streamlines can express flow rate.Meanwhile,to solve the problem of obvious boundaries when stitching image,we change the streamline tracking constraints.When a white noise is used as an input in an unsteady flow field,double value scattering is used to enhance the contrast of streamlines;moreover,the"cross"high-pass filtering is also adopt instead of two-dimensional high-pass filtering.Finally,we apply the above methods to a case of the surface wave field in typhoon condition.Our experimental results show that applying the methods can generate high-quality wave images and animations.Therefore,it is helpful to understand and study waves in typhoon condition to avoid the potential harm of the waves to people's lives and property.
