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Æ×ØÓÒ ÖÙÚÞ ÖÒÚ´ÓÒÒØÖ×ÑÒ××ѵÖÓÚ¹ ÓÒÒÚÒØÔÐ∂cÔÐÓØ»ÙÖº×℄4/26s13i∂t = D i∆c×ØÓÙÚÓÓÙ´½¼ÑµºÐÓÙÓÙÓÒÒØÖÙÐÒÝÖÓÚÒÍ ÞºÓ¹ÓÐÙÚÚ Ð´Úõ×ÐÓÙÔ½¼ÑµÓÔØÖÒÔÚÖ×ØÚÑi∆ = ⃗∇· ⃗∇ = ∂2∂x 2 + ∂2∂y 2 + ∂2∂z 2ÔÓÐÓÚÒÓÒÒØÖÙÒ∂c∂t = D ∂ 2 ci∂x 2 c(x,0) =c(x,t) = c 02 + 2c 0π− 1 ( ) (3πx3 cos exp − 32 π 2 )l l 2 Dt[( πxcosl){c0 x < l/20 x > l/2exp(− π2l 2Dt )Ñ×+ 1 ( ) (5πx5 cos exp − 52 π 2 ) ]l l 2 Dt ···