In this paper, a new finite element method for the flow analysis of the viscous incompressible power-law fluid is proposed by the use of penalty-hybrid/mixed finite element formulation and by the introduction of an al...In this paper, a new finite element method for the flow analysis of the viscous incompressible power-law fluid is proposed by the use of penalty-hybrid/mixed finite element formulation and by the introduction of an alternative perturbation, which is weighted by viscosity, of the continuity equation. A numerical example is presented to exhibit the efficiency of the method.展开更多
Fluid flow analysis, such as gas flow analysis, water flow analysis, etc., is a fundamental problem in integrated energy systems (IES). Datasets are significant for researchers to test their proposed models and algori...Fluid flow analysis, such as gas flow analysis, water flow analysis, etc., is a fundamental problem in integrated energy systems (IES). Datasets are significant for researchers to test their proposed models and algorithms for fluid flow analysis. In this paper, we provide multiple benchmark datasets of fluid systems with detailed topology and operation information, such as data of fluid supply, fluid demand, pipes, valves, compressors/pumps, physical operation limits, etc. The provided benchmark datasets have synthetic and practical fluid systems of different scales, including gas systems with numbers of nodes ranging from 11 to 4197 and water systems with numbers of nodes ranging from 7 to 1894. Then, the data format of the datasets is described. Finally, fluid flow results on different benchmark systems under several typical scenarios are analyzed.展开更多
A fluid–structure interaction method combining a nonlinear finite element algorithm with a preconditioning finite volume method is proposed in this paper to simulate parachute transient dynamics. This method uses a t...A fluid–structure interaction method combining a nonlinear finite element algorithm with a preconditioning finite volume method is proposed in this paper to simulate parachute transient dynamics. This method uses a three-dimensional membrane–cable fabric model to represent a parachute system at a highly folded configuration. The large shape change during parachute inflation is computed by the nonlinear Newton–Raphson iteration and the linear system equation is solved by the generalized minimal residual（GMRES） method. A membrane wrinkling algorithm is also utilized to evaluate the special uniaxial tension state of membrane elements on the parachute canopy. In order to avoid large time expenses during structural nonlinear iteration, the implicit Hilber–Hughes–Taylor（HHT） time integration method is employed. For the fluid dynamic simulations, the Roe and HLLC（Harten–Lax–van Leer contact） scheme has been modified and extended to compute flow problems at all speeds. The lower–upper symmetric Gauss–Seidel（LUSGS） approximate factorization is applied to accelerate the numerical convergence speed. Finally,the test model of a highly folded C-9 parachute is simulated at a prescribed speed and the results show similar characteristics compared with experimental results and previous literature.展开更多
The decay of weakly swirling flows in a type of cross-section-varying pipes was discussed analytically. For laminar swirling flow, the feature of exponential decay was demonstrated. For turbulent swirling flow, in spi...The decay of weakly swirling flows in a type of cross-section-varying pipes was discussed analytically. For laminar swirling flow, the feature of exponential decay was demonstrated. For turbulent swirling flow, in spite of the decay of circulation flux, a necessary condition for local circulation to amplify along downstream was obtained under the Boussinesq's hypothesis.展开更多
文摘In this paper, a new finite element method for the flow analysis of the viscous incompressible power-law fluid is proposed by the use of penalty-hybrid/mixed finite element formulation and by the introduction of an alternative perturbation, which is weighted by viscosity, of the continuity equation. A numerical example is presented to exhibit the efficiency of the method.
基金supported by the Science and Technology Project of State Grid Corporation of China(5400-202199524A-O-5-ZN).
文摘Fluid flow analysis, such as gas flow analysis, water flow analysis, etc., is a fundamental problem in integrated energy systems (IES). Datasets are significant for researchers to test their proposed models and algorithms for fluid flow analysis. In this paper, we provide multiple benchmark datasets of fluid systems with detailed topology and operation information, such as data of fluid supply, fluid demand, pipes, valves, compressors/pumps, physical operation limits, etc. The provided benchmark datasets have synthetic and practical fluid systems of different scales, including gas systems with numbers of nodes ranging from 11 to 4197 and water systems with numbers of nodes ranging from 7 to 1894. Then, the data format of the datasets is described. Finally, fluid flow results on different benchmark systems under several typical scenarios are analyzed.
文摘A fluid–structure interaction method combining a nonlinear finite element algorithm with a preconditioning finite volume method is proposed in this paper to simulate parachute transient dynamics. This method uses a three-dimensional membrane–cable fabric model to represent a parachute system at a highly folded configuration. The large shape change during parachute inflation is computed by the nonlinear Newton–Raphson iteration and the linear system equation is solved by the generalized minimal residual（GMRES） method. A membrane wrinkling algorithm is also utilized to evaluate the special uniaxial tension state of membrane elements on the parachute canopy. In order to avoid large time expenses during structural nonlinear iteration, the implicit Hilber–Hughes–Taylor（HHT） time integration method is employed. For the fluid dynamic simulations, the Roe and HLLC（Harten–Lax–van Leer contact） scheme has been modified and extended to compute flow problems at all speeds. The lower–upper symmetric Gauss–Seidel（LUSGS） approximate factorization is applied to accelerate the numerical convergence speed. Finally,the test model of a highly folded C-9 parachute is simulated at a prescribed speed and the results show similar characteristics compared with experimental results and previous literature.
文摘The decay of weakly swirling flows in a type of cross-section-varying pipes was discussed analytically. For laminar swirling flow, the feature of exponential decay was demonstrated. For turbulent swirling flow, in spite of the decay of circulation flux, a necessary condition for local circulation to amplify along downstream was obtained under the Boussinesq's hypothesis.
