A pde question that contains fourier series

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SUMMARY

The discussion revolves around solving a partial differential equation (PDE) using Fourier series. The specific problem involves boundary conditions defined as u(x,0) = x, u(x,2) = 0, u(0,y) = 0, and du(1,y)/dx = 0, with the equation [d²u/dx²] + [d²u/dy²] = 0. The user has attempted various values for k in the context of Fourier series but has not achieved a solution. A suggested approach involves treating the problem as an eigenvalue problem, leading to the equation X'' - λX = 0 with boundary conditions X(0) = 0 and X'(1) = 0, where λ = -μ² yields nonzero eigenvalues.

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bcyalcin
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i have been trying to solve a pde problem for 3 days but i couldn't even find the answer,now i feel i m about to have a mental disease,anyone can help me ?the question is

u(x,0) = x

u(x,2) = 0

u(0,y) = 0

d u(1,y) / dx = 0
[ d^2 u / dx^2 ] + [ d^2 u / dy^2 ] = 0

i will really be appreciate if someone help me,for long time i have been working on this
p.s. i have tried for k > 0 and k < 0 but couldn't find anything,the only thing about what happens when k = 0 is we obtain linear equations like F(x) = Ax + B and G(y) = Cy + D,but i have no idea what i wil do in Fourier series with these
 
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bcyalcin said:
i have been trying to solve a pde problem for 3 days but i couldn't even find the answer,now i feel i m about to have a mental disease,anyone can help me ?


the question is

u(x,0) = x

u(x,2) = 0

u(0,y) = 0

d u(1,y) / dx = 0



[ d^2 u / dx^2 ] + [ d^2 u / dy^2 ] = 0




i will really be appreciate if someone help me,for long time i have been working on this



p.s. i have tried for k > 0 and k < 0 but couldn't find anything,the only thing about what happens when k = 0 is we obtain linear equations like F(x) = Ax + B and G(y) = Cy + D,but i have no idea what i wil do in Fourier series with these

If ##U(x,y) = X(x)Y(y)## your X eigenvalue problem becomes$$
X'' - \lambda X = 0, X(0) = 0, X'(1) = 0$$If you let ##\lambda = -\mu^2##, you should find nonzero eigenvalues.
 

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