Tamed stability of finite difference schemes for the transport equation on the half-line

04/05/2023

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by   Lucas Coeuret, et al.

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In this paper, we prove that, under precise spectral assumptions, some finite difference approximations of scalar leftgoing transport equations on the positive half-line with numerical boundary conditions are ℓ^1-stable but ℓ^q-unstable for any q>1. The proof relies on the accurate description of the Green's function for a particular family of finite rank perturbations of Toeplitz operators whose essential spectrum belongs to the closed unit disk and with a simple eigenvalue of modulus 1 embedded into the essential spectrum.