Similarity solutions of partial differential equations using DESOLV

2007 ◽  
Vol 176 (11-12) ◽  
pp. 682-693 ◽  
Author(s):  
K.T. Vu ◽  
J. Butcher ◽  
J. Carminati
2011 ◽  
Vol 2011 ◽  
pp. 1-13
Author(s):  
Mario Lefebvre

Two-dimensional diffusion processes are considered between concentric circles and in angular sectors. The aim of the paper is to compute the probability that the process will hit a given part of the boundary of the stopping region first. The appropriate partial differential equations are solved explicitly by using the method of similarity solutions and the method of separation of variables. Some solutions are expressed as generalized Fourier series.


2000 ◽  
Vol 61 (3) ◽  
pp. 507-521 ◽  
Author(s):  
C. Sophocleous

In this paper potential symmetries are sought of the inhomogeneous nonlinear diffusion equations ut = x1−M[xN−1f (u) ux]x. The functional forms of f (u) that admit such symmetries are completely classified. A complete list is presented of the symmetries, which depend on the values of the parameters M and N. We give examples of similarity solutions using potential symmetries. In some cases, the potential symmetries enable us to convert non–invertible mappings of nonlinear partial differential equations to linear ones.


2019 ◽  
Vol 74 (10) ◽  
pp. 869-877 ◽  
Author(s):  
Andronikos Paliathanasis

AbstractWe study a nonlinear system of partial differential equations that describe rotating shallow water with an arbitrary constant polytropic index γ for the fluid. In our analysis, we apply the theory of symmetries for differential equations, and we determine that the system of our study is invariant under a five-dimensional Lie algebra. The admitted Lie symmetries form the $\left\{{2{A_{1}}{\ \oplus_{s}}\ 2{A_{1}}}\right\}{\ \oplus_{s}}\ {A_{1}}$ Lie algebra for γ ≠ 1 and $2{A_{1}}{\ \oplus_{s}}\ 3{A_{1}}$ for γ = 1. The application of the Lie symmetries is performed with the derivation of the corresponding zero-order Lie invariants, which applied to reduce the system of partial differential equations into integrable systems of ordinary differential equations. For all the possible reductions, the algebraic or closed-form solutions are presented. Travel-wave and scaling solutions are also determined.


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