Effect of thermal fluctuations on the average shape of a graphene nanosheet suspended in a shear flow

S Gravelle and C Kamal and L Botto, ACTA MECHANICA, 236, 5803-5813 (2025).

DOI: 10.1007/s00707-024-04190-9

Graphene nanosheets display relatively large hydrodynamic slip lengths in most solvents and, because of this, adopt a stable orientation in a shear flow, instead of rotating, when the effect of thermal fluctuations is not too large (Kamal et al. in Nat Commun 11(1):2425, 2020). In this paper, we combine molecular dynamics simulations and continuum boundary integral simulations to demonstrate that the time-averaged 'S' shape adopted by a flexible graphene nanosheet subject to moderate thermal fluctuation is almost identical to the shape predicted for negligible thermal fluctuations. The stable 'S' shape adopted by the particle results primarily from the normal hydrodynamic traction, which is sensitive to the orientation of the particle with respect to the flow direction. Our 2D results imply that thermally-induced shape fluctuations may have a relatively minor effect on the time-averaged rheology of dilute suspensions of graphene nanosheets for relatively large but finite P & eacute;clet numbers.

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