Can some one help me for converting three or two coupled pdes to odes using Lie group or any other method in maple

i want to solve these two coupled eqaut with finite boundary conditionsions. Can some one help me

eq1:=diff(f(eta),eta,eta,eta,eta)+2*(epsilon/(1+epsilon*theta(eta)))^2*diff(f(eta),eta,eta)*((diff(theta(eta),eta))^2)-(epsilon/(1+epsilon*theta(eta)))*(diff(theta(eta),eta,eta))*(diff(f(eta),eta,eta))=0;

eq2:=diff(theta(eta),eta,eta)+Pr*Re*f(eta)*diff(theta(eta),eta)=0;

Re:=1:Pr:=1:epsilon:=0.25:

bc:=f(1)=0,D(f)(-1)=0,D(f)(1)=1,D(f)(-1)=1,theta(-1)=0,theta(1)=0;

Can some one help me " How to conert a three or four coupled equation by using non dimensions variable "

Dear, need help about Implicit finite difference method 

plz reply as soon as possible

Thanks

psi = x^(4/5)*f(x, eta)/(1+x)^(1/20)

eta = y/(x^(1/5)*(1+x)^(1/20))

how can i (diff(psi, x))

how can i (diff(psi, y))