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Abstract This article presents the new version of the backward substitution method (BSM) for simulating transfer in anisotropic and inhomogeneous media governed by linear and fully nonlinear advection–diffusion-reaction equations (ADREs). The key idea of the method is to formulate a general analytical expression of the solution in the form of the series over a basis system which satisfies the boundary conditions with any choice of the free parameters. The radial basis functions (RBFs) of the different types are used to generate the basis system for expressing the solution. Then the expression is substituted into the ADRE under consideration and the free parameters are determined by the collocation inside the solution domain. As a result we separate the approximation of the boundary conditions and the approximation of the PDE inside the solution domain. This approach leads to an important improvement of the accuracy of the approximate solution and can be easily extended onto irregular domain problems. Furthermore, the proposed method is extended to general fully nonlinear ADREs in combination with the quasilinearization technique. Some numerical results and comparisons are provided to justify the advantages of the proposed method. [ABSTRACT FROM AUTHOR]

Highlights • A new accurate meshless method is proposed for time-dependent fully nonlinear problems. • The obtained solutions are remarkable better than the ones obtained using other techniques. • The proposed method can be easily extended to general high order nonlinear problems. Abstract In this paper, a new meshless semi-analytical collocation technique is presented for the simulation of time-dependent linear and fully nonlinear advection diffusion reaction equations (ADREs). The time-dependent nonlinear problem is reduced to the system of linear problems in each time layer by using the quasilinearization technique in combination with the Crank–Nicolson scheme for the temporal approximation. Then it may be solved by the meshless backward substitution method. In the backward substitution method the approximation is given to satisfy the boundary conditions as a prior. Then the approximation is substituted back to the governing equations where the unknown weighted parameters are obtained using the collocation approach. The developed method has been tested on seven concrete problems for a range of free parameters. The comparison of the obtained numerical results with those available in literatures reveals that the proposed method can accurately approximate linear and nonlinear advection diffusion reaction problems. This method can also be easily extended onto other linear and nonlinear transient problems in 1D, 2D, and 3D due to its general idea and easy implementation. [ABSTRACT FROM AUTHOR]

This paper has presented a new semi-analytic numerical method for solving multi-point problems for nonlinear singular ordinary differential equations (ODEs) of a high order. The method consists of replacing the original equation by an approximate equation which has an exact analytic solution with a set of free parameters. These free parameters are determined by the use of the collocation procedure. Some examples are given to demonstrate the validity and applicability of the new method and a comparison is made with the existing results. In particular, the singular multi-point boundary value problems (BVPs) with equations of the fourth, fifth and sixth orders are considered. Numerical results show that the proposed method is of high accuracy and is efficient for solving a wide class of the nonlinear singular ODEs. The algorithm of the method is very simple and does not require any specific technique in handling the singularity at the endpoints of the solution domain. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents a new meshless in space numerical method – the method of approximate fundamental solutions (MAFS) for solving problems with moving boundaries of the Stefan type. This technique first suggested for solving the Stefan problems in plane geometry is now extended onto the cases of inward and outward spherical problems. Computed results for the inward and outward spherical problems are numerically evaluated for comparison with the results obtained by other authors. The comparison shows that the method presented provides a very high precision in determining the position of the moving boundary and the results are in a good agreement with the previous studies. [Copyright &y& Elsevier]

Abstract: The paper presents a new meshless numerical technique for solving one-dimensional problems with moving boundaries including the Stefan problems. The technique presented is based on the use of the delta-shaped functions and the method of approximate fundamental solutions (MAFS) firstly suggested for solving elliptic problems and for heat equations in domains with fixed boundaries. The numerical examples are presented and the results are compared with analytical solutions. The comparison shows that the method presented provides a very high precision in determining the position of the moving boundary even for a region that initially has zero thickness. [Copyright &y& Elsevier]