How to solve a fourth order PDE2D inhomogeneous biharmonic equation with ndsolveNDSolve
?
I tried the following code:
P[x_, y_] := x y
eq = Laplacian[Laplacian[w[x, y], {x, y}], {x, y}] == x*y;
bc = {w[0, y] == w[1, y] == w[x, 0] == w[x, 1] == 0,
Derivative[2, 0][w][0, y] == Derivative[2, 0][w][1, y] ==
Derivative[0, 2][w][x, 0] == Derivative[0, 2][w][x, 1] == 0};
NDSolve[{eq == P[x, y], bc}, w, {x, 0, 1}, {y, 0, 1}]
but it says
NDSolve::femcmsd: The spatial derivative order of the PDE may not exceed two.
How to derive the solution?