# Question:Maple can't solve my partial differential equation

## Question:Maple can't solve my partial differential equation

Maple 2019

hi i did this in maple and i get an error when i try to solve the system of equation  :

restart;
with(Student[VectorCalculus]);
with(PDEtools);with(plots);

h_f := 300;
h_a := 1000;
T_f := 1500 + 273;
T_a := 30 + 273;
k_r := 15;
k_s := 70;
Ra := 5;
Rf := 6.05;
Rc := 6;

Lap1 := Laplacian(T_r(r, theta), polar[r, theta]);
Lap2 := Laplacian(T_s(r, theta), polar[r, theta]);
Bc_r := k_r*eval(Gradient(T_r(r, theta), polar[r, theta])[1], r = 5) = h_a*(T_r(5, theta) - T_a);
Bc_s := k_s*eval(Gradient(T_s(r, theta), polar[r, theta])[1], r = 6.05) = h_f*(T_s(6.05, theta) - T_f);
systemThermal_r := Lap1 = 0;
systemThermal_s := Lap2 = 0;
Bc1_rs := eval(T_r(r, theta), r = 6) = eval(T_s(r, theta), r = 6);
Bc2_rs := k_r*eval(Gradient(T_r(r, theta), polar[r, theta])[1], r = 6) = -k_s*eval(Gradient(T_s(r, theta), polar[r, theta])[1], r = 6);
pdsolve([systemThermal_r, systemThermal_s, Bc_r, Bc_s, Bc1_rs, Bc2_rs]);

Error, (in PDEtools:-Library:-NormalizeBoundaryConditions) unable to isolate the functions {T_r(5, theta), T_r(6, theta), T_s(6, theta), T_s(6.05, theta), (D[1](T_r))(5, theta), (D[1](T_r))(6, theta), (D[1](T_s))(6, theta), (D[1](T_s))(6.05, theta)} in the given boundary conditions {15*(D[1](T_r))(5, theta) = 1000*T_r(5, theta)-303000, 15*(D[1](T_r))(6, theta) = -70*(D[1](T_s))(6, theta), 70*(D[1](T_s))(6.05, theta) = 300*T_s(6.05, theta)-531900, T_r(6, theta) = T_s(6, theta)}

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