指数同伦法对Cauchy条件下变系数Burgers方程的解析与数值分析

Analytical and Numerical Investigation of the Variable Coefficient Burgers Equation Under Cauchy Condition With the Exponential Homotopy Method

使用近似解析法来研究在给定初始条件和边界条件下变系数Burgers方程,引入一种新式同伦来解决微分方程中由变系数带来的问题,这种新同伦比传统方法计算更高效,并能给出时域上的一致解析表达式.分别计算了有限空间域上变系数Burgers方程的解析解,讨论了在有限空间区域上激波的形成,并对所得解析解进行了范数意义下收敛性研究的探索.基于Lie(李)变换群理论,研究了该方程的对称性质,给出了其无穷小生成子,守恒律和群不变解.文中给出的解是从非线性偏微分方程中直接得到的,未经过行波变换.通过"h-curve"准则探讨了近似解的收敛性.通过有限差分法进行直接数值模拟,已验证该方法的准确性和有效性.

The variable coefficient Burgers equation was studied with an approximate analytical method under the given initial and boundary conditions. A new-form homotopy was introduced to overcome the problem brought by the variable coefficient, this new-form homotopy enhanced the computational efficiency in comparison with the traditional forms, and gave a consistent an- alytical solution expression in time domain. Analytical solutions to the variable coefficient Bur- gem equation in finite space domain were determined respectively, and shock wave formation in finite space domain was also discussed. Convergence of the presented analytical solution was explored in the sense of norm. Based on the Lie transformtion group theory, symmetry of the variable coefficient Burgers equation was studied with its infinitesimal generators, conservation law and group invariant solution obtained. The presented solution was directly deduced from the nonlinear partial differential equation without travelling wave transformation. Convergence of the approximate analytical solution was discussed with the so-called ＇ h-curve＇ criteria. Di- rect numerical simulation with the finite difference method proves accuracy and effectiveness of the proposed exponential homotopy method.