Hello @xzczd
These PDEs are giving me too much trouble,
Clear[Ra, Pr, n, pde1, pde2, pde3]
pde2[Ra_, Pr_, n_] =
u[x, y]*(D[v[x, y], x]) + v[x, y]*D[v[x, y], y] ==
Pr*D[D[v[x, y], x]^(n - 1)*D[v[x, y], x], x] + Ra*Pr*T[x, y];
pde3 = u[x, y]*D[T[x, y], x] + v[x, y]*D[T[x, y], y] ==
D[T[x, y], x, x];
With[{eps = 10^-3},
pde1 = D[u[x, y], x] + D[v[x, y], y] == D[v[x, y], y]*eps];
bcs = {{u[x, 0] == 0, v[x, 0] == 0, T[x, 0] == 0}, {u[-1/2, y] == 0,
v[-1/2, y] == 0, T[-1/2, y] == 1/2}, {u[1/2, y] == 0,