Rotational dynamics of a neutrally suspended cubic particle and passive scalar transport in simple shear flow

Through high-fidelity numerical simulations based on a lattice Boltzmann framework, we conduct an extensive investigation into the rotational dynamics of a cubic particle in simple shear flow and the resulting advective transport of a passive scalar from the particle. This study spans a range of Reynolds numbers from 0.1 to 10 and Schmidt numbers from 10 to 1000. The research focuses on several key aspects: the transition of a cubic particle from an initial non-equilibrium state to an equilibrium state at varying Reynolds numbers; the characteristics of the cubic particle's equilibrium states; and the fluid dynamics and passive scalar transport properties induced by particle rotation in the equilibrium state. Several key findings have emerged: 1) A general linear relationship exists between the change in angular velocity around any principal axis and the sine of the orientation angle of that axis during the transition to equilibrium. 2) Cubic particles display distinct equilibrium states at low versus high Reynolds numbers, with more complex flow patterns at lower Reynolds numbers. 3) The rotating cube's edges create a flow pattern with a sharp angle pointing downstream, facilitating the advective transport of passive scalars. 4) The cube's rotation induces intricate transport mechanisms, resulting in a passive scalar release pattern that differs from spheres. These phenomena are analyzed in depth.