关于边界层方法
On the Boundary Layer Methods
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摘要: 本文指出传统的边界层方法(包括匹配法和Višik—Lyusternik方法)的不足:不能作出边界层项的渐近展开式.提出多重尺度构造边界层项的方法,得到符合实情的结果.又与Levinson所用的方法比较,本方法能更简单地导出后一方法给出的边界层项的渐近展开式.又应用此方法研究现有的关于奇异摄动的某些成果,指出这些成果的局限性,并在一般情况下作出解的渐近展开式.Abstract: In this paper, the defect of the traditionary boundary layer methods (including the method of matched asymptotic expansions and the method of Višik-Lyusternik) is noted, from those methods we can not construct the asymptotic expansion of boundary layer term substantially. So the method of multiple scales is proposed for constructing the asymptotic expansion of boundary layer term, the reasonable result is obtained. Furthermore, we compare this method with the method used by Levin-son, and find that both methods give the same asymptotic expansion of boundary layer term, but our method is simpler.Again, we apply this method to study some known works on singular perturbations. The limitations of those works have been noted, and the asymptotic expansion of solution is constructed in general condition.
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[1] 列别捷夫,H H.,《特殊函数及其应用》,(中译本),高等教育出版社,(1975). [2] Nayfeh,A.H.,Perturbation Methods,John Wiley and Sons,New York,(1973). [3] Mahony,J.J.,An expansion mathod for singular perturbation problems,J.Australian Math.Soc.,2,(1962),440-463. [4] Fowkes,N.D.,A singular perturbation method,Part I and Ⅱ,Quart.Appl.Math.,26,(1968),57-69,71-85. [5] Levinson,N.,The first boundary value problem for εΔu+A(x,y)ux+B(x,y)uy+C(x,y)u=D(x,y),Annals of Math.,51,2,(1950),428-445. [6] Comstock,C.,Singular perturbations of elliptic equations,SIAM J.Appl.Math.,20,(1971),491-502. [7] 江福汝,关于椭圆型方程的奇摄动,复旦学报(自然科学版),第2期,(1978),29-37.
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