# Question:Non-linear PDE problem

## Question:Non-linear PDE problem

Maple 15
`Hey everyone. The last few days I work on a non-linear PDE. `
`U*`&PartialD;`(F(s))/`&PartialD;`(x) = -k*sigma*cos(theta)*`&PartialD;`(F(s)*kro(s)*`&PartialD;`(J(s))/`&PartialD;`(x))/(`&mu;o`*sqrt(k/phi)*`&PartialD;`(x));`
`with boundary conditions: when x=-∞: s=swi       and  `
`x=L : U*dF(s)+k*sigma*F(s)*kro(s)*`&PartialD;`(J(s))/(`&mu;o`*sqrt(k/phi)*`&PartialD;`(x))`
`I need to plot s over x ,  whare  swi<s<1-sor   and 0<x<L`
`I have writen the following equations that calculate all parameters of the PDE.`
`> restart;   > krowi := 1; krwor := .1; aw := 1.16; ao := 3.69; alpha := 0.6e-1; U := 2.9374109836-10^(-7); L := 0.552566e-1; m := .5; sor := .3; swi := .25; k := 10^(-14); `&mu;w` := 0.1e-2; `&mu;o` := 0.5e-2; sigma := 0.72e-1; phi := .3; theta := 0;> C := krowi*(1-sor-swi)^(-ao); > A := krwor*(1-sor-swi)^(-aw); > krw(s):=A*(s-swi)^(aw): > kro(s):=C*(1-sor-s)^(ao): > F(s):=((krw(s))/(muw))/((krw(s))/(muw)+(kro(s))/(muo)): > J(s):=alpha[((s-swi)/(1-sor-swi))^(-1/(m))-1]^(1-m): > PDE:=U*`&PartialD;`(F(s))/`&PartialD;`(x) = -k*sigma*cos(theta)*`&PartialD;`(F(s)*kro(s)*`&PartialD;`(J(s))/`&PartialD;`(x))/(`&mu;o`*sqrt(k/phi)*`&PartialD;`(x));`
`When I try different methos, most time I get this message:`
`Error, (in pdsolve/info) first argument is not a differential equation`
`Any suggestions?`
`Thank you`
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