On the transport limit of singularly perturbed convection–diffusion problems on networks. (9th December 2020)

• Record Type: Journal Article
• Authors: Egger, Herbert; Philippi, Nora
• Is Part Of: Mathematical methods in the applied sciences. Volume 44:Number 6(2021)
• Page Start: 5005
• Page End: 5020
• Publication Date: 2020-12-09
• Subjects: asymptotic analysis -- diffusion and convection (76R05) -- partial differential equations on networks -- singular perturbations in the context of PDEs (35B25); Mathematics -- Periodicals; Technology -- Mathematics -- Periodicals; 519
• DOI: 10.1002/mma.7084
• Languages: English
• ISSNs: 0170-4214

Abstract

Abstract : We consider singularly perturbed convection–diffusion equations on one‐dimensional networks (metric graphs) as well as the transport problems arising in the vanishing diffusion limit. Suitable coupling conditions at inner vertices are derived that guarantee conservation of mass and dissipation of a mathematical energy which allows us to prove stability and well‐posedness. For single intervals and appropriately specified initial conditions, it is well‐known that the solutions of the convection–diffusion problem converge to that of the transport problem with order O ( ϵ ) in the L ∞ ( L 2 )‐norm with diffusion ϵ → 0. In this paper, we prove a corresponding result for problems on one‐dimensional networks. The main difficulty in the analysis is that the number and type of coupling conditions changes in the singular limit which gives rise to additional boundary layers at the interior vertices of the network. Since the values of the solution at these network junctions are not known a priori, the asymptotic analysis requires a delicate choice of boundary layer functions that allows to handle these interior layers.