Eigenvalue Problems for Elliptic Type Partial Differential Operators with Spectral Parameter Contained Linearly in Boundary Conditions

1999 ◽  
pp. 319-333 ◽  
Author(s):  
Boris Belinskiy
Keyword(s):  
Boundary Conditions ◽  
Spectral Parameter ◽  
Differential Operators ◽  
Eigenvalue Problems ◽  
Elliptic Type ◽  
Partial Differential ◽  
Partial Differential Operators

Solving 2D boundary-value problems using discrete partial differential operators

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Marcin Jaraczewski ◽  
Tadeusz Sobczyk
Keyword(s):  
Finite Difference ◽  
Differential Equations ◽  
Boundary Conditions ◽  
Boundary Value Problems ◽  
Differential Operators ◽  
Boundary Value ◽  
Partial Differential ◽  
Content Type ◽  
Partial Derivatives ◽  
Partial Differential Operators

Purpose Discrete differential operators of periodic base functions have been examined to solve boundary-value problems. This paper aims to identify the difficulties of using those operators to solve ordinary linear and nonlinear differential equations with Dirichlet and Neumann boundary conditions. Design/methodology/approach This paper presents a promising approach for solving two-dimensional (2D) boundary problems of elliptic differential equations. To create finite differential equations, specially developed discrete partial differential operators are used to replace the partial derivatives in the differential equations. These operators relate the value of the partial derivatives at each point to the value of the function at all points evenly distributed over the area where the solution is being sought. Exemplary 2D elliptic equations are solved for two types of boundary conditions: the Dirichlet and the Neumann. Findings An alternative method has been proposed to create finite-difference equations and an effective method to determine the leakage flux in the transformer window. Research limitations/implications The proposed approach can be classified as an extension of the finite-difference method based on the new formulas approximating the derivatives. This method can be extended to the 3D or time-periodic 2D cases. Practical implications This paper presents a methodology for calculations of the self- and mutual-leakage inductances for windings arbitrarily located in the transformer window, which is needed for special transformers or in any case of the internal asymmetry of windings. Originality/value The presented methodology allows us to obtain the magnetic vector potential distribution in the transformer window only, for example, to omit the magnetic core of the transformer from calculations.

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