000170044 001__ 170044 000170044 005__ 20260316092630.0 000170044 0247_ $$2doi$$a10.1016/j.newton.2025.100373 000170044 0248_ $$2sideral$$a148622 000170044 037__ $$aART-2026-148622 000170044 041__ $$aeng 000170044 100__ $$0(orcid)0000-0002-9361-4794$$aDe Corato, Marco$$uUniversidad de Zaragoza 000170044 245__ $$aColloidal Magnus effect in polymer solutions 000170044 260__ $$c2026 000170044 5060_ $$aAccess copy available to the general public$$fUnrestricted 000170044 5203_ $$aRotating particles moving in fluids undergo a transverse migration via the inertia-induced Magnus effect. This phenomenon vanishes at colloidal scales because inertia is negligible and the fluid flow is time reversible. Yet, recent experiments discovered an inverse Magnus effect of colloids in polymeric and micellar solutions, supposedly because their viscoelasticity breaks the time reversibility. Our study shows that classical viscoelastic features—stress relaxation, normal-stress differences, and/or shear thinning—cannot explain this phenomenon. Instead, it originates from local polymer density inhomogeneities due to their stress-gradient-induced transport, a mechanism increasingly important at smaller scales—indeed, relevant to colloidal experiments. Incorporating this mechanism into our model leads to quantitative agreement with the experiments without fitting parameters. Our work provides new insights into colloidal motion in complex fluids with microstructural inhomogeneities, offers a simple mechanistic theory for predicting the resulting migration, and underscores the necessity of assimilating these findings in future designs of micro-machinery, such as those including swimmers, actuators, or rheometers. 000170044 536__ $$9info:eu-repo/grantAgreement/ES/MCIU/PID2022-139803NB-I00$$9info:eu-repo/grantAgreement/ES/MICINN/RYC2021-030948-I 000170044 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttps://creativecommons.org/licenses/by/4.0/deed.es 000170044 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000170044 700__ $$aZhang, Kun 000170044 700__ $$aZhu, Lailai 000170044 7102_ $$15001$$2600$$aUniversidad de Zaragoza$$bDpto. Ciencia Tecnol.Mater.Fl.$$cÁrea Mecánica de Fluidos 000170044 773__ $$g2, [13 pp.] (2026), 100373$$tNewton$$x2950-6360 000170044 8564_ $$s3717121$$uhttps://zaguan.unizar.es/record/170044/files/texto_completo.pdf$$yVersión publicada 000170044 8564_ $$s1586160$$uhttps://zaguan.unizar.es/record/170044/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000170044 909CO $$ooai:zaguan.unizar.es:170044$$particulos$$pdriver 000170044 951__ $$a2026-03-16-08:17:31 000170044 980__ $$aARTICLE