[100 points] The two-dimensional Laplace equation around a cylinder with a domain [0, 2Ï]Ã[1, 5] is given
by.
â
2Ï
âx2
+
â
2Ï
ây2
1
r
â
âr
r
âÏ
âr
+
1
r
2
â
2Ï
âθ2
= 0 (1)
The analytical solution is given by
Ï(r, θ) = Uâ
r â
R2
r
sin(θ) (2)
(3)
In here R = 1 and Uâ = 1. The Drichlet boundary conditions:
Ï(1, θ) = 0 (4)
Ï(5, θ) =
5 â
1
5
sin(θ) (5)
(6)
Use the second-order accurate finite difference discretization with uniform 81Ã41, 161Ã81 and 321Ã161
meshes to solve the above Laplace equation. For this purpose
- Implement the fully implicit solution algorithm and use a direct solver (LU factorization) to solve.
- Implement Jacobi, Gauss-Seidel and SOR algorithms and compare their convergence rates with the
iteration numbers. - Plot Error function versus the mesh space âx in a log-log scale. Compute the spatial convergence
rate.
The error function is given by
Error = kÏi,j â Ïanalytick2
â
imaxjmax
(7)
[20 points] Why we should not use the following skewed Laplace operator to solve the Laplace equation
in Cartesian coordinates?
â2u =
â4ui,j + ui+1,j+1 + uiâ1,jâ1 + uiâ1,j+1 + ui+1,jâ1
2âx
2
= 0
Sample Solution