# Numerical investigations on self-similar solutions of the nonlinear diffusion equation

Yibao Li, Junseok Kim

Research output: Contribution to journalArticle

### Abstract

In this paper, we present the numerical investigations of self-similar solutions for the nonlinear diffusion equation ht=-(h 3hxxx)x, which arises in the context of surface-tension-driven flow of a thin viscous liquid film. Here, h=h(x,t) is the liquid film height. A self-similar solution is h(x,t)=h(α(t)(x-x 0)+ x0, t0)=f(α(t)(x-x0)) and α(t)=[1-4A(t-t0)]-1/4, where A and x0 are constants and t0 is a reference time. To discretize the governing equation, we use the Crank-Nicolson finite difference method, which is second-order accurate in time and space. The resulting discrete system of equations is solved by a nonlinear multigrid method. We also present efficient and accurate numerical algorithms for calculating the constants, A, x 0, and t0. To find a self-similar solution for the equation, we numerically solve the partial differential equation with a simple step-function-like initial condition until the solution reaches the reference time t0. Then, we take h(x,t0) as the self-similar solution f(x). Various numerical experiments are performed to show that f(x) is indeed a self-similar solution.

Original language English 30-36 7 European Journal of Mechanics, B/Fluids 42 https://doi.org/10.1016/j.euromechflu.2013.05.003 Published - 2013 Nov 1

### Fingerprint

Nonlinear Diffusion Equation
Self-similar Solutions
Numerical Investigation
multigrid methods
step functions
Liquid
eccentrics
liquids
Crank-Nicolson
partial differential equations
Step function
Multigrid Method
interfacial tension
Discrete Systems
Surface Tension
Numerical Algorithms
Difference Method
System of equations
Governing equation
Finite Difference

### Keywords

• Nonlinear multigrid method
• Self-similar solution
• Thin film

### ASJC Scopus subject areas

• Physics and Astronomy(all)
• Mathematical Physics

### Cite this

In: European Journal of Mechanics, B/Fluids, Vol. 42, 01.11.2013, p. 30-36.

Research output: Contribution to journalArticle

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