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A class of nonlinear reaction-diffusion-convection equations describing various processes in physics, biology, chemistry etc. is under study in the case of time and two space variables. The group of equivalence transformations is…

Analysis of PDEs · Mathematics 2020-04-23 Roman Cherniha , Mykola Serov , Yulia Prystavka

Lie group method provides an efficient tool to solve a differential equation. This paper suggests a fractional partner for fractional partial differential equations using a fractional characteristic method. A space-time fractional diffusion…

Mathematical Physics · Physics 2010-09-22 Guo-cheng Wu

We prove an energy inequality for nonlocal diffusion operators of the following type, and some of its generalisations: $Lu (x) := \int_{\mathbb{R}^N} K(x,y) (u(y) - u(x)) dy$, where $L$ acts on a real function $u$ defined on $\mathbb{R}^N$,…

Analysis of PDEs · Mathematics 2019-10-22 J. A. Cañizo , A. Molino

In this paper, a complete Lie symmetry analysis of the damped wave equation with time-dependent coefficients is investigated. Then the invariant solutions and the exact solutions generated from the symmetries are presented. Moreover, a Lie…

Differential Geometry · Mathematics 2018-09-21 Rohollah Bakhshandeh Chamazkoti , Mohsen Alipour

In this work we consider the identifiability of two coefficients $a(u)$ and $c(x)$ in a quasilinear elliptic partial differential equation from observation of the Dirichlet-to-Neumann map. We use a linearization procedure due to Isakov [On…

Analysis of PDEs · Mathematics 2015-06-16 Herbert Egger , Jan-Frederik Pietschmann , Matthias Schlottbom

The (1+1)-dimensional nonlinear boundary value problem, modeling the process of melting and evaporation of metals, is studied by means of the classical Lie symmetry method. All possible Lie operators of the nonlinear heat equation, which…

Mathematical Physics · Physics 2012-11-30 Roman Cherniha , Sergii Kovalenko

Many important applications are available for nonlinear reaction-diffusion equation especially in the area of biology and engineering. Therefore a mathematical model for Lie symmetry reduction of system of nonlinear reaction-diffusion…

Mathematical Physics · Physics 2007-05-23 Sanjeev Kumar , Ravendra Singh

In this paper we are concerned with the matrix Li-Yau-Hamilton estimates for nonlinear heat equations. Firstly, we derive such estimate on a K\"{a}hler manifold with a fixed K\"{a}hler metric. Then we consider the estimate on K\"{a}hler…

Differential Geometry · Mathematics 2019-11-05 Xin-An Ren

We study the long time behavior of bounded, integrable solutions to a nonlocal diffusion equation, $\partial _t u=J*u-u$, where $J$ is a smooth, radially symmetric kernel with support $B_d(0)\subset\mathbb{R}^2$. The problem is set in an…

Analysis of PDEs · Mathematics 2015-04-29 Carmen Cortázar , Manuel Elgueta , Fernando Quirós , Noemi Wolanski

We study invariant solutions of a certain class of time-fractional diffusion-wave equations with variable coefficients via Lie symmetry analysis. In physics, the fractional diffusion equation describes transport dynamics that are governed…

We analyse the underlying nonlinear partial differential equation which arises in the study of gravitating flat fluid plates of embedding class one. Our interest in this equation lies in discussing new solutions that can be found by means…

General Relativity and Quantum Cosmology · Physics 2015-05-19 A. M. Msomi , K. S. Govinder , S. D. Maharaj

Splitting methods are a widely used numerical scheme for solving convection-diffusion problems. However, they may lose stability in some situations, particularly when applied to convection-diffusion problems in the presence of an unbounded…

Numerical Analysis · Mathematics 2024-04-25 Thi Tam Dang , Trung Hau Hoang , Giandomenico Orlandi

We obtain a Li-Yau-type estimate for nonnegative ancient solutions to the subcritical semilinear heat equation $\frac{\p u}{\p t}=\De u+u^p$ in $\rz^n\times(-\infty,0)$. Then, we combine the Li-Yau type estimate and Melre-Zaag's result to…

Analysis of PDEs · Mathematics 2026-05-14 Yang Zhou

The theory of plasma physics offers a number of nontrivial examples of partial differential equations, which can be successfully treated with symmetry methods. We propose the Grad-Shafranov equation which may illustrate the reciprocal…

Analysis of PDEs · Mathematics 2017-01-24 Mehdi Nadjafikhah , Parastoo Kabi-Nejad

We study the symmetry reduction of nonlinear partial differential equations with two independent variables. We propose new ans\"atze reducing nonlinear evolution equations to system of ordinary differential equations. The ans\"atze are…

Analysis of PDEs · Mathematics 2017-12-27 Ivan Tsyfra , Tomasz Czyżycki

A new definition of conditional invariance for boundary value problems involving a wide range of boundary conditions (including initial value problems as a special case) is proposed. It is shown that other definitions worked out in order to…

Mathematical Physics · Physics 2014-12-23 Roman Cherniha , John R King

This paper presents a new Lie theoretic approach to fractal calculus, which in turn yields such new results as a Fractal Noether's Theorem, a setting for fractal differential forms, for vector fields, and Lie derivatives, as well as…

We investigated the analytical solution of fractional order K(m,n) type equation with variable coefficient which is an extended type of KdV equations into a genuinely nonlinear dispersion regime. By using the Lie symmetry analysis, we…

Analysis of PDEs · Mathematics 2020-06-16 H. Jafari , N. Kadkhoda , D. Baleanu

Exact solutions for nonlinear Arrhenius reaction-diffusion are constructed in $n$ dimensions. A single relationship between nonlinear diffusivity and the nonlinear reaction term leads to a nonclassical Lie symmetry whose invariant solutions…

Analysis of PDEs · Mathematics 2016-02-17 P. Broadbridge , B. H. Bradshaw-Hajek , D. Triadis

We provide a simple method for obtaining new Liouville theorems for scaling invariant superlinear parabolic problems with gradient structure. To illustrate the method we prove Liouville theorems (guaranteeing nonexistence of positive…

Analysis of PDEs · Mathematics 2015-04-21 Pavol Quittner