With the definition of generalized potential temperature, a new generalized frontogenesis function, which is expressed as the Lagrangian change rate of the magnitude of the horizontal generalized potential temperature...With the definition of generalized potential temperature, a new generalized frontogenesis function, which is expressed as the Lagrangian change rate of the magnitude of the horizontal generalized potential temperature gradient, is derived. Such a frontogenesis function is more appropriate for a real moist atmosphere because it can reflect frontogenesis processes, in which the atmosphere in a frontal zone is typically characterized by neither completely dry nor uniform saturation. Furthermore, by derivation, the expression of generalized frontogenesis function includes both temperature and humidity gradients, which is different from and superior to the traditional frontogenesis function in moist processes, which also uses equivalent potential temperature. Diagnostic studies of real cases are performed and show that the generalized frontogenesis function in non- uniformly saturated moist atmosphere indeed provides a useful tool for frontogenesis, compared to using the traditional frontogenesis function. The new frontogenesis function can be used in situations involving either a strong temperature or moisture gradient and is closely correlated with precipitation.展开更多
A new frontogenesis function is developed and analyzed on the basis of a local change rate of the absolute horizontal gradient of the resultant deformation. Different from the traditional frontogenesis function, the n...A new frontogenesis function is developed and analyzed on the basis of a local change rate of the absolute horizontal gradient of the resultant deformation. Different from the traditional frontogenesis function, the newly defined deformation frontogenesis is derived from the viewpoint of dynamics rather than thermodynamics. Thus, it is more intuitive for the study of frontogenesis because the compaction of isolines of both temperature and moisture can be directly induced by the change of a flow field. This new frontogenesis function is particularly useful for studying the mei-yu front in China because mei-yu rainbands typically consist of a much stronger moisture gradient than temperature gradient, and involve large deformation flow. An analysis of real mei-yu frontal rainfall events indicates that the deformation frontogenesis function works remarkably well, producing a clearer mei-yu front than the traditional frontogenesis function based on a measure of the potential temperature gradient. More importantly, the deformation frontogenesis shows close correlation with the subsequent（6 h later） precipitation pattern and covers the rainband well, bearing significance for the prognosis or even prediction of future precipitation.展开更多
Elastic composites containing liquid inclusions exist widely in nature and engineering fields. The volumetric response of liquid inclusions is important in many cases, such as an isolated cell embedded in an extracell...Elastic composites containing liquid inclusions exist widely in nature and engineering fields. The volumetric response of liquid inclusions is important in many cases, such as an isolated cell embedded in an extracellular matrix and an oil pocket embedded within shale. In this study, we developed a model for describing the volumetric response of an ellipsoidal liquid inclusion. Specifically, we investigated the volumetric response of an ellipsoidal liquid inclusion embedded in a three-dimensional (3D) matrix through an analytical expression of the volumetric response. We performed parametric analysis and found that loading along the shortest axis can induce the most volume change, while loading along the longest axis can induce the least volume change. We also found that the volumetric response decreases with increasing Poisson ratio of the matrix. These results could be used to understand some cell behavior in a 3D matrix, for example, cell alignment under mechanical load.展开更多
An upwind weak Galerkin finite element scheme was devised and analyzed in this article for convection-dominated Oseen equations. The numerical algorithm was based on the weak Galerkin method enhanced by upwind stabili...An upwind weak Galerkin finite element scheme was devised and analyzed in this article for convection-dominated Oseen equations. The numerical algorithm was based on the weak Galerkin method enhanced by upwind stabilization. The resulting finite element scheme uses equal-order, say k, polynomial spaces on each element for the velocity and the pressure unknowns. With finite elements of order k≥1, the numerical solutions are proved to converge at the rate of O(h^(k+1/2)) in an energy-like norm for convection-dominated Oseen equations. Numerical results are presented to demonstrate the accuracy and effectiveness of the upwind weak Galerkin scheme.展开更多
基金supported by the National 973 Fundamental Research Program of the Ministry of Science and Technology of China (Grant No.2013CB430105)the Special Scientific Research Fund of the Meteorological Public Welfare of the Ministry of Sciences and Technology (Grant No.GYHY201406003)+1 种基金the National Natural Sciences Foundation of China (Grant Nos.41375054, 41375052 and 40805001)the Opening Foundation of the State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences (Grant Nos.2012LASW-B02 and 2013LASW-A06)
文摘With the definition of generalized potential temperature, a new generalized frontogenesis function, which is expressed as the Lagrangian change rate of the magnitude of the horizontal generalized potential temperature gradient, is derived. Such a frontogenesis function is more appropriate for a real moist atmosphere because it can reflect frontogenesis processes, in which the atmosphere in a frontal zone is typically characterized by neither completely dry nor uniform saturation. Furthermore, by derivation, the expression of generalized frontogenesis function includes both temperature and humidity gradients, which is different from and superior to the traditional frontogenesis function in moist processes, which also uses equivalent potential temperature. Diagnostic studies of real cases are performed and show that the generalized frontogenesis function in non- uniformly saturated moist atmosphere indeed provides a useful tool for frontogenesis, compared to using the traditional frontogenesis function. The new frontogenesis function can be used in situations involving either a strong temperature or moisture gradient and is closely correlated with precipitation.
基金supported by the National 973 Fundamental Research Program of the Ministry of Science and Technology of China (Grant No. 2013CB430105)the Key Research Program of the Chinese Academy of Sciences (Grant No. KZZD-EW-05-01)+2 种基金the Special Scientific Research Fund of the Meteorological Public Welfare of the Ministry of Sciences and Technology, China (Grant No. GYHY201406003)the National Natural Science Foundation of China (Grant Nos. 41375054, 41375052 and 40805001)the Opening Foundation of the State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences (Grant Nos. 2012LASW-B02 and 2013LASW-A06)
文摘A new frontogenesis function is developed and analyzed on the basis of a local change rate of the absolute horizontal gradient of the resultant deformation. Different from the traditional frontogenesis function, the newly defined deformation frontogenesis is derived from the viewpoint of dynamics rather than thermodynamics. Thus, it is more intuitive for the study of frontogenesis because the compaction of isolines of both temperature and moisture can be directly induced by the change of a flow field. This new frontogenesis function is particularly useful for studying the mei-yu front in China because mei-yu rainbands typically consist of a much stronger moisture gradient than temperature gradient, and involve large deformation flow. An analysis of real mei-yu frontal rainfall events indicates that the deformation frontogenesis function works remarkably well, producing a clearer mei-yu front than the traditional frontogenesis function based on a measure of the potential temperature gradient. More importantly, the deformation frontogenesis shows close correlation with the subsequent（6 h later） precipitation pattern and covers the rainband well, bearing significance for the prognosis or even prediction of future precipitation.
基金the National Natural Science Foundation of China (Grants 11522219 and 11532009)the National Institutes of Health (Grant U01EB016422)+1 种基金the National Science Foundation through the ScienceTechnology Center for Engineering Mechanobiology (Grant CMMI 1548571).
文摘Elastic composites containing liquid inclusions exist widely in nature and engineering fields. The volumetric response of liquid inclusions is important in many cases, such as an isolated cell embedded in an extracellular matrix and an oil pocket embedded within shale. In this study, we developed a model for describing the volumetric response of an ellipsoidal liquid inclusion. Specifically, we investigated the volumetric response of an ellipsoidal liquid inclusion embedded in a three-dimensional (3D) matrix through an analytical expression of the volumetric response. We performed parametric analysis and found that loading along the shortest axis can induce the most volume change, while loading along the longest axis can induce the least volume change. We also found that the volumetric response decreases with increasing Poisson ratio of the matrix. These results could be used to understand some cell behavior in a 3D matrix, for example, cell alignment under mechanical load.
基金supported by Postdoctoral Research Foundation of China(Grant No.2022M721054)the Natural Science Foundation of Henan Province of China(Grant No.222300420213).
文摘An upwind weak Galerkin finite element scheme was devised and analyzed in this article for convection-dominated Oseen equations. The numerical algorithm was based on the weak Galerkin method enhanced by upwind stabilization. The resulting finite element scheme uses equal-order, say k, polynomial spaces on each element for the velocity and the pressure unknowns. With finite elements of order k≥1, the numerical solutions are proved to converge at the rate of O(h^(k+1/2)) in an energy-like norm for convection-dominated Oseen equations. Numerical results are presented to demonstrate the accuracy and effectiveness of the upwind weak Galerkin scheme.
