# Error in solving a system of partial differential equations

I'm trying to a solve of system of partial differential equation, but Mathematica is giving some error. Can anyone help me please to find out the error.

EQ1 = (1/P*r)*D[T[y, τ], {y, 2}] +
u[y, τ]*D[T[y, τ], {y, 1}] + -2*T[y, τ]*
D[u[y, τ], {y, 1}] - S*D[T[y, τ], {τ, 1}] +
EE*c*(D[u[y, τ], {y, 2}])^2;
EQ2 = D[u[y, τ], {y, 3}] + u[y, τ]*D[u[y, τ], {y, 2}] -
S*D[u[y, τ], {y, 1}, {τ, 1}] - (D[
u[y, τ], {y, 1}])^2;
INC1 = Derivative[1, 0][u][0, τ] - Sin[τ];
INC2 = T[0, τ] - 1;
INC3 = u[0, τ];
EE = 1; c = 1; P = 1; r = 1; S = 1; NDSolve[{EQ1 == 0, EQ2 == 0,
INC1 == 0, INC2 == 0, INC3 == 0}, {u, T}, {τ, 0, 10}, {y, -10,
10}]


I'm not sure what you are trying to model here, but there's not enough initial and boundary conditions for the system to be solved. I tried to just add a few, this works but I'm not sure exactly which initial and boundary conditions you need for your problem

(*your eqs and conditions*)
INC4 = Derivative[1, 0][T][0, τ];
INC5 = Derivative[2, 0][u][0, τ];
INC6 = u[y, 0] + T[y, 0];

NDSolve[{EQ1 == 0, EQ2 == 0, INC1 == 0, INC2 == 0, INC3 == 0,
INC4 == 0, INC5 == 0, INC6 == 0}, {u, T}, {τ, 0, 10}, {y, -10,
10}]

• thanks @luigi for your effort, but code is not working again if I add the initial conditions you have mentioned. – MMS Oct 7 '20 at 18:39
• Initial conditions and boundary conditions need to be consistent. – anderstood Oct 8 '20 at 8:38