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-   -   Diagonal storage for c-grid airfoil possible? (https://www.cfd-online.com/Forums/main/11407-diagonal-storage-c-grid-airfoil-possible.html)

 zonexo May 10, 2006 10:13

Diagonal storage for c-grid airfoil possible?

hi,

i'm trying to solve the sys of linear eqns due to flow past a c-grid airfoil. due to the structure of c-grid, it is folded such that it touches itself, resulting in coordinate cut.

becuase of this, it is not possible to use the diagonal storage for the "A" matrix. Besides increase in memory, iteration is also slower when using other forms of matrix storage such as compressed sparse row.

is there any way (reorder, ghost cell etc) which can be done to enable the use of diagonal storage? any hints will be welcomed.

tks!

 Bounecer May 10, 2006 13:43

Re: Diagonal storage for c-grid airfoil possible?

I've written a fortran code program to study 2D, incompressible viscous flow about airfoil, i've used structured C-grid generation and discretized the flow equations in numerical domain with finite volume method. I've introduced SIMPLER algorithm and used second order UPWIND scheem for convective terms. I've obtained a pentadiagonal system, with sweeping and TDMA (tridiagonal matrix algorithm) i've solved the system. My program run with verry small relaxation parameters (5*10**-2), but when the difference between two consecutive values of velocity is (10**-4) it diverges

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