Concentration-dependent diffusion in a semi-infinite medium

✍ Scribed by D.F. Hays; H.N. Curd

• Publisher: Elsevier Science
• Year: 1967
• Tongue: English
• Weight: 494 KB
• Volume: 283
• Category: Article
• ISSN: 0016-0032
• DOI: 10.1016/0016-0032(67)90045-2

✦ Synopsis

A uar&?ionaJ jormuka.tkm is presented which has aa it.8 E&r-Lagrange equatim the fundamental partial differentti equ&on of diffusion. This variational ex~e&on is applicable for both timedepend& and timeindependent boundary cond&ms and for a diffusion coe$cient which is a junction of the concentratian. This variatienal technique is applied to the problem of unidimension al diffusion

in a semi-in$ntie isotropic medium whe+re the diffuzrion coe&ient is strongly depend.& upon the wncent7ation of the diflueer. To solve the ex&mum problem, a system of "natura+?" $nite diflertmee equations is established as a consequence of the variatthzl expre&m. Curves of concentration ratio us distance are calculated and compared with a formal exact solution for a specific diffukon coe$cient.