Chiara Giraudo

• Ferri, Samuele; Giraudo, Chiara; Loi, Valerio; Kuchta, Miroslav & Serra-Capizzano, Stefano (2026). Spectral analysis of the stiffness matrix sequence in the approximated Stokes equation. Boletín de la Sociedad Matemática Mexicana. ISSN 1405-213X. 32(3). doi: 10.1007/s40590-026-00935-9. Full text in Research Archive Show summary

  In the present paper, we analyse in detail the spectral features of the matrix sequences arising from the Taylor–Hood P2 - P1 approximation of variable viscosity for the 2D Stokes problem under weak assumptions on the regularity of the diffusion. Localization and distributional spectral results are provided, accompanied by numerical tests and visualizations. A preliminary study of the impact of our findings on the preconditioning problem is also presented. A final section with concluding remarks and open problems ends the current work.

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• Giraudo, Chiara; Gjerde, Ingeborg Gåseby & Scott, L. Ridgway (2023). Kinetic energy flow instability analysis applied to Poiseuille pipe flow. doi: https:/fenicsproject.org/fenics-2023/. Full text in Research Archive Show summary

  In this work, we present simulation results that shed light on the instability of Poiseuille pipe flow. While linearized instability analysis indicates that pipe flow is stable for any Reynolds number, laboratory experiments show the existence of a critical Reynolds number at which pipe flow becomes unstable. To address this discrepancy, we implemented the Kinetic Energy Flow Instability method, first introduced by Reynolds and Orr. This method is based on the variational formulation of the PDE and takes the form of an eigenvalue problem. Via solving this problem with FEniCS and SLEPc, we identified a critical Reynolds number which serves as an upper bound for stable pipe flow. Finally, we will also show early results obtained using an homotopy method, which provides insight on the development of turbulent pipe flow. Finansiering uten prosjekt; Kilde: EC/H2020; Referanse: 945371

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