TY - JOUR
T1 - Effect of hydrodynamic slip on the rotational dynamics of a thin Brownian platelet in shear flow
AU - Kamal, Catherine
AU - Gravelle, Simon
AU - Botto, Lorenzo
PY - 2021
Y1 - 2021
N2 - The classical theory by Jeffery predicts that, in the absence of Brownian fluctuations, a thin rigid platelet rotates continuously in a shear flow, performing periodic orbits. However, a stable orientation is possible if the surface of the platelet displays a hydrodynamic slip length comparable to or larger than the thickness of the platelet. In this article, by solving the Fokker-Plank equation for the orientation distribution function and corroborating the analysis with boundary integral simulations, we quantify a threshold Péclet number, above which such alignment occurs. We found that for smaller than, but larger than a second threshold, a regime emerges where Brownian fluctuations are strong enough to break the platelet's alignment and induce rotations, but with a period of rotation that depends on the value of. For below this second threshold, slip has a negligible effect on the orientational dynamics. We use these thresholds to classify the dynamics of graphene-like nanoplatelets for realistic values of and apply our results to the quantification of the orientational contribution to the effective viscosity of a dilute suspension of nanoplatelets with slip. We find a non-monotonic variation of this term, with a minimum occurring when the slip length is comparable to the thickness of the particle.
AB - The classical theory by Jeffery predicts that, in the absence of Brownian fluctuations, a thin rigid platelet rotates continuously in a shear flow, performing periodic orbits. However, a stable orientation is possible if the surface of the platelet displays a hydrodynamic slip length comparable to or larger than the thickness of the platelet. In this article, by solving the Fokker-Plank equation for the orientation distribution function and corroborating the analysis with boundary integral simulations, we quantify a threshold Péclet number, above which such alignment occurs. We found that for smaller than, but larger than a second threshold, a regime emerges where Brownian fluctuations are strong enough to break the platelet's alignment and induce rotations, but with a period of rotation that depends on the value of. For below this second threshold, slip has a negligible effect on the orientational dynamics. We use these thresholds to classify the dynamics of graphene-like nanoplatelets for realistic values of and apply our results to the quantification of the orientational contribution to the effective viscosity of a dilute suspension of nanoplatelets with slip. We find a non-monotonic variation of this term, with a minimum occurring when the slip length is comparable to the thickness of the particle.
KW - Key words suspensions
KW - particle/fluid flow
UR - http://www.scopus.com/inward/record.url?scp=85106482617&partnerID=8YFLogxK
U2 - 10.1017/jfm.2021.327
DO - 10.1017/jfm.2021.327
M3 - Article
AN - SCOPUS:85106482617
SN - 0022-1120
VL - 919
JO - Journal of Fluid Mechanics
JF - Journal of Fluid Mechanics
M1 - A1
ER -