2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/200823We compute the time evolution of elliptic flow in non-central relativistic heavy-ion collisions, using a (2+1)-dimensional code with longitudinal boost-invariance to simulate viscous fluid dynamics in the causal Israel-Stewart formulation. We show that even ``minimal'' shear viscosity eta/s=hbar/(4pi) leads to a large reduction of elliptic flow compared to ideal fluid dynamics, raising questions about the interpretation of recent experimental data from the Relativistic Heavy Ion Collider.5 pages, incl. 4 figures. Fig.2 redrawn, several footnotes and references added. This version accepted by Physics Letters BNuclear Theorytext