Thanks Alec you are right ......but the problem can't still be solved. I even tried to solve it with only two system of differential equations but still i came up with an error. here is my new trial and the error:

> sys5:=[10^6*v(x,y)*diff(T(x,y),x)-0.1*diff(T(x,y),y,y)-10^3*diff(v(x,y),y)^2=0,diff(v(x,y),x)=0];
> IBC:= {v(0,y) = 150, v(x,1) = 300, T(x,0) =400, T(0.3,y) =350,T(-0.3,y)=400};
> pds := pdsolve(sys5,IBC,[T,v],numeric);
Error, (in pdsolve/numeric/process_PDEs) number of dependent variables and number of PDE must be the same

I would appriciate any of your suggestions,

thanks in advance,

bruke