A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate e...A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate expression of multiple integrals of a continuous function defined in a three-dimensional bounded domain is proposed by combining wavelet expansion and Lagrange boundary extension.Through applying such an integral technique,during the solution of nonlinear partial differential equations,the unknown function and its lower-order partial derivatives can be approximately expressed by its highest-order partial derivative values at nodes.A set of nonlinear algebraic equations with respect to these nodal values of the highest-order partial derivative is obtained using a collocation method.The validation and convergence of the proposed method are examined through several benchmark problems,including the eighth-order two-dimensional and fourth-order three-dimensional boundary value problems and the large deflection bending of von Karman plates.Results demonstrate that the present method has higher accuracy and convergence rate than most existing numerical methods.Most importantly,the convergence rate of the proposed method seems to be independent of the order of the differential equations,because it is always sixth order for second-,fourth-,sixth-,and even eighth-order problems.展开更多
The Coiflet wavelet-homotopy Galerkin method is extended to solve unsteady nonlinear wave equations for the first time.The Korteweg-de Vries(KdV)equation,the Burgers equation and the Korteweg-de Vries-Burgers(KdVB)equ...The Coiflet wavelet-homotopy Galerkin method is extended to solve unsteady nonlinear wave equations for the first time.The Korteweg-de Vries(KdV)equation,the Burgers equation and the Korteweg-de Vries-Burgers(KdVB)equation are examined as illustrative examples.Validity and accuracy of the proposed method are assessed in terms of relative variance and the maximum error norm.Our results are found in good agreement with exact solutions and numerical solutions reported in previous studies.Furthermore,it is found that the solution accuracy is closely related to the resolution level and the convergence-control parameter.It is also found that our proposed method is superior to the traditional homotopy analysis method when dealing with unsteady nonlinear problems.It is expected that this approach can be further used to solve complicated unsteady problems in the fields of science and engineering.展开更多
In this paper,the natural convection of a complex fluid that contains both nanoparticles and gyrotactic microorganisms in a heated square cavity is considered.The Buongiorno model is applied to descirbe the nanofluid ...In this paper,the natural convection of a complex fluid that contains both nanoparticles and gyrotactic microorganisms in a heated square cavity is considered.The Buongiorno model is applied to descirbe the nanofluid behaviours.Both the top and bottom horizontal walls of the cavity are adiabatic,and there is a temperature difference between the left and right vertical walls.The non-dimensional governing equations are obtained when the stream-vorticity formulation of function is used,which are solved by the recently developed robust Coiflet wavelet homotopy analysis method.A rigid verification for the solver is given.Besides,the effects of various physics parameters including the Rayleigh number,the buoyancy ratio parameter,the bioconvection Rayleigh number,the Prandtl number,the Brownian motion parameter,the thermophoresis parameter,the heat generation parameter,the Lewis number,the bioconvection Peclet number and the Schmidt number on this complicated natural convection are examined.It is known that natural convection is closely related to our daily life owing to its wide existence in nature and engineering applications.We believe that our work will make a significant contribution to a better understanding of the natural convection of a complex fluid in a cavity with suspensions of both inorganic nanoparticles and organic microorganisms.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11925204 and 12172154)the 111 Project(Grant No.B14044)the National Key Project of China(Grant No.GJXM92579).
文摘A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate expression of multiple integrals of a continuous function defined in a three-dimensional bounded domain is proposed by combining wavelet expansion and Lagrange boundary extension.Through applying such an integral technique,during the solution of nonlinear partial differential equations,the unknown function and its lower-order partial derivatives can be approximately expressed by its highest-order partial derivative values at nodes.A set of nonlinear algebraic equations with respect to these nodal values of the highest-order partial derivative is obtained using a collocation method.The validation and convergence of the proposed method are examined through several benchmark problems,including the eighth-order two-dimensional and fourth-order three-dimensional boundary value problems and the large deflection bending of von Karman plates.Results demonstrate that the present method has higher accuracy and convergence rate than most existing numerical methods.Most importantly,the convergence rate of the proposed method seems to be independent of the order of the differential equations,because it is always sixth order for second-,fourth-,sixth-,and even eighth-order problems.
文摘The Coiflet wavelet-homotopy Galerkin method is extended to solve unsteady nonlinear wave equations for the first time.The Korteweg-de Vries(KdV)equation,the Burgers equation and the Korteweg-de Vries-Burgers(KdVB)equation are examined as illustrative examples.Validity and accuracy of the proposed method are assessed in terms of relative variance and the maximum error norm.Our results are found in good agreement with exact solutions and numerical solutions reported in previous studies.Furthermore,it is found that the solution accuracy is closely related to the resolution level and the convergence-control parameter.It is also found that our proposed method is superior to the traditional homotopy analysis method when dealing with unsteady nonlinear problems.It is expected that this approach can be further used to solve complicated unsteady problems in the fields of science and engineering.
基金H.Xu is supported by the National Natural Science Foundation of China(Grant No.11872241)This work was partially supported by the Australian Research Council(ARC)through Grants DE150100169,FT160100357 and CE140100003。
文摘In this paper,the natural convection of a complex fluid that contains both nanoparticles and gyrotactic microorganisms in a heated square cavity is considered.The Buongiorno model is applied to descirbe the nanofluid behaviours.Both the top and bottom horizontal walls of the cavity are adiabatic,and there is a temperature difference between the left and right vertical walls.The non-dimensional governing equations are obtained when the stream-vorticity formulation of function is used,which are solved by the recently developed robust Coiflet wavelet homotopy analysis method.A rigid verification for the solver is given.Besides,the effects of various physics parameters including the Rayleigh number,the buoyancy ratio parameter,the bioconvection Rayleigh number,the Prandtl number,the Brownian motion parameter,the thermophoresis parameter,the heat generation parameter,the Lewis number,the bioconvection Peclet number and the Schmidt number on this complicated natural convection are examined.It is known that natural convection is closely related to our daily life owing to its wide existence in nature and engineering applications.We believe that our work will make a significant contribution to a better understanding of the natural convection of a complex fluid in a cavity with suspensions of both inorganic nanoparticles and organic microorganisms.
