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In this study, the dynamic response of a neutrally buoyant elliptical cylinder is investigated for a two‐dimensional shear flow over a wide range of aspect ratios (rb/ra, where, ra and rb are the major and minor axis radii, respectively). Parametric studies were carried out for confinement ratios (k=2ra/H) that vary the distance between the particle and the domain walls (H) for shear‐rate (G) based Reynolds number Re=ra2Gρf/μf. The simulations were performed using the signed distance field‐immersed boundary method (SDFIBM) algorithm implemented in OpenFOAM. The motion of the particle is limited to free rotation about the z axis through the centroid without any translational freedom. This work demonstrates and affirms two distinct responses of the elliptical particle in shear flow: (1) a periodical rotating stage that exhibits a relaxation type of response and (2) a spontaneously locked stationary stage, where the net torque becomes zero. A critical Reynolds number (Recr) demarcates the transition between these two stages, and it depends on aspect ratio and confinement ratio. The prediction of Recr was found to be in excellent agreement with the experimentally reported data in the literature, validating the SDFIBM for particles subjected to shear flows. [ABSTRACT FROM AUTHOR]

In the present study, the impingement process of alginate droplet on an immiscible liquid is investigated using experimental and numerical approaches. The results reveal that the intensity of interaction between the two immiscible liquids leads to formation of different droplet shapes after impingement. The droplet yield stress, Ohnesorge number (Oh), and Weber number (We) were found to be the chief parameters which determine the droplet shape after impingement. Three discernible shapes of droplets could be identified from the present investigation: (i) spherical ball, (ii) spherical ball with a tail, and (iii) a toroidal shape. A detailed parameter regime map has been constructed which aids in identifying these three droplet shapes in well‐defined range of Oh and We. Besides, the numerical investigations carried out also helped in deciphering the temporal evolution of the pressure, velocity and kinetic energy fields associated with the drop impingement process. [ABSTRACT FROM AUTHOR]

This simulation study explores the two‐fluid model's (TFM) capability to reproduce the alternating bubble patterns in a sinusoidal pulsed fluidized bed (PFB). Simulations were performed with frictional limits ranging between 0.58–0.62 with the inlet gas frequency being varied in the range of 3–6 Hz. The preliminary investigations showed that the Johnson and Jackson frictional model with a frictional limit of 0.61 yields a regular bubble pattern. The inference of this regular bubble pattern was based on the discrete Fourier analysis of the temporal pressure signals obtained at different spatial locations inside the PFB. Although the one‐dimensional temporal pressure signals characterized a regular bubble pattern behaviour, the staggered bubbles visually observed were highly unstable. Moreover, in‐depth insights into the PFB's regime classification showed that the predicted regular bubble patterns are susceptible to uncertainties due to the inherent mathematical limitations of the frictional closures of the TFM. Besides, the combinations of the frictional models/ limits in the TFM simulations could not predict the high stability and intermediate stability regimes of PFB. The present investigations helped identify the limitations of frictional closure models of TFM in predicting the regular bubble patterns and the regime classification for the PFB. It also expresses the need to develop better strategies to model the frictional closure of TFM to accurately account for the ever‐evolving dense and dilute particle regions of a PFB. [ABSTRACT FROM AUTHOR]