Drag on prolate spheroids in wall-bounded shear flow

The dynamics of non-spherical particles in wall-bounded flows plays a fundamental role in numerous natural and industrial processes, such as pollen dispersion, fibre suspensions and biomedical flows. Predictive simulations of such systems often employ an Euler–Lagrange approach, for which the accuracy hinges on the drag model used. Although reliable correlations exist for particles in unbounded flow or in direct contact with a wall, the intermediate regime of finite wall distance has received little attention, despite its prevalence in practical applications. For prolate spheroids – a common non-spherical particle shape – the drag force in this regime results from a complex interplay among the particle Reynolds number, the wall-normal distance and the particle’s three-dimensional orientation. In this work, we develop a drag model for prolate spheroids (aspect ratio lamda equals 2 <mml:math xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest" xmlns:cup="http://contentservices.cambridge.org" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:m="http://cambridge.org/core/metadata" xmlns:core="http://cambridge.org/core" xmlns:c="http://cambridge.org/core/content"> <mml:mi>λ</mml:mi> <mml:mo>=</mml:mo> <mml:mn>2</mml:mn> </mml:math> $\lambda = 2$ ) that incorporates these coupled effects through a hierarchical framework based on three reference orientations and wall correction factors. The formulation recovers the exact unbounded Stokes behaviour and establishes near-wall asymptotic limits. Validation against direct numerical simulations across the parameter space considered yields a mean relative error below 2 %. Within its validated range, the proposed model accurately captures orientation-dependent wall effects for drag predictions, and is applicable in Euler–Lagrange simulations of non-spherical particles in wall-bounded flows.