Highly nonnormal eigenproblems in the aeronautical industry

We consider a large-scale nonnormal eigenvalue problem that occurs in flutter analysis. Matrices arising in such problems are usually sparse, of large order, and highly nonnormal. We use the incomplete Arnoldi method associated with the Tchebycheff acceleration in order to compute a subset of the eigenvalues and their associated eigenvectors. This method has been parallelized using BLAS kernels and has been tested on various vector and parallel machines. We also studied the stability of the eigenproblem by perturbing the original matrix and verified that the spectral instability increases with the size of the problem. This work has been conducted at CERFACS in cooperation with the Aerospatiale Avions (Structural research and development department).