The coefficient of restitution of some pharmaceutical tablets/compacts

Bharadwaj, Rahul; Smith, Carlowen Andrew; Hancock, Bruno C.

doi:10.1016/j.ijpharm.2010.09.018

Cited by 41 publications

(17 citation statements)

References 24 publications

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“…For different kinds of coated tablets they found CoR values that ranged from 0.4 to 0.9 (30). For polystyrene balls, a value of 0.81 was approximated as CoR (19).…”

Section: Coefficient Of Restitutionmentioning

confidence: 99%

Experimental Analysis of Tablet Properties for Discrete Element Modeling of an Active Coating Process

et al. 2013

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Abstract. Coating of solid dosage forms is an important unit operation in the pharmaceutical industry. In recent years, numerical simulations of drug manufacturing processes have been gaining interest as process analytical technology tools. The discrete element method (DEM) in particular is suitable to model tabletcoating processes. For the development of accurate simulations, information on the material properties of the tablets is required. In this study, the mechanical parameters Young's modulus, coefficient of restitution (CoR), and coefficients of friction (CoF) of gastrointestinal therapeutic systems (GITS) and of activecoated GITS were measured experimentally. The dynamic angle of repose of these tablets in a drum coater was investigated to revise the CoF. The resulting values were used as input data in DEM simulations to compare simulation and experiment. A mean value of Young's modulus of 31.9 MPa was determined by the uniaxial compression test. The CoR was found to be 0.78. For both tablet-steel and tablet-tablet friction, active-coated GITS showed a higher CoF compared with GITS. According to the values of the dynamic angle of repose, the CoF was adjusted to obtain consistent tablet motion in the simulation and in the experiment. On the basis of this experimental characterization, mechanical parameters are integrated into DEM simulation programs to perform numerical analysis of coating processes.

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“…For different kinds of coated tablets they found CoR values that ranged from 0.4 to 0.9 (30). For polystyrene balls, a value of 0.81 was approximated as CoR (19).…”

Section: Coefficient Of Restitutionmentioning

confidence: 99%

Experimental Analysis of Tablet Properties for Discrete Element Modeling of an Active Coating Process

et al. 2013

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“…There is the significance of the choice of the value of the coefficient of restitution, e = 0.2 (e.g., pharmaceutical compacts; see for example (Bharadwaj et al 2010) [25] and the fluid viscosity of η = 0.985 Pa-s (e.g., castor oil) with density similar to that of water in the simulation results presented here to highlight the interactions between highly inelastic "soft" collisions in the presence of moderately high fluid viscosity. These choices were made to allow the assembly simulations to reach "steady-state" within a reasonable computational time frame; see for example, Koenders, et al (2001) [26].…”

Section: Comparison Of Large-scale Simulation Resultsmentioning

confidence: 99%

Improving Conductivity in Nano-Conduit Flows by Using Thermal Pulse-Induced Brownian Motion: A Spectral Impulse Intensity Approach

Tüzün

2019

Applied Sciences

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Featured Application: Nanoparticle suspensions are used in a variety of applications involving the transport of reagents and products to and from structured material surfaces. The more efficient alignment of particle layers adjacent to, and in contact with, a reactive surface, such as found in a fuel cell, bio-medical and electrochemical device, is often reliant upon the effective control of the dynamics of particle assembly in narrow conduits. One such control is possible by spectral thermal pulsing to generate a controlled Brownian motion of particles. This is demonstrated by numerical simulation here to be highly effective when particles are conveyed in viscous fluids close to a neutrally buoyant condition. Abstract: Inter-particle and particle-wall connectivity in suspension flow has profound effects on thermal and electrical conductivity. The spectral impulse generation and the imparting of kinetic energy on the particles is shown through a mathematical analysis to be effective as a means of achieving an approximate equivalent of a Langevin thermostat. However, with dilute suspensions, the quadratic form of the thermal pulse spectra is modified with a damping coefficient to achieve the desired Langevin value. With the dense suspension system, the relaxation time is calculated from the non-linear differential equation, and the fluid properties were supported by the viscosity coefficient. A "smoothed" pulse is used for each time-step of the flow simulation to take care of the near-neighbor interactions of the adjacent particles. An approximate optimal thermostat is achieved when the number of extra pulses introduced within each time step is found to be nearly equal to the co-ordination number of each particle within the assembly. Furthermore, the ratio of the particle kinetic energy and the thermal energy imparted is found to be never quite equal to unity, as they both depend upon the finite values of the pulse duration and the relaxation time.well as providing uniform surface scaffolds for varied environmental emission detection and separation devices. Previous work using pore-scale CFD simulations (see for example Crevacore et al. 2017) [3] has investigated the effects of varying the direction of the acceleration due to gravity on colloidal suspensions from orthogonal to parallel to the fluid flow direction, and the resulting impact on Brownian motion and particle settling.Albert Einstein (1956) [4] formulated the mathematical framework for the kinetics of the Brownian motion of particles in suspension by considering the auto-correlation of fluctuating velocities and the spectral density of the intensity of fluctuations. It is possible to augment the physics of pressure-driven dense assembly flows of near-neutrally buoyant particles by combining the effects of (i) the lubrication forces due to the conveying fluid-immersed particle interactions and (ii) the drag forces due to fluid viscosity with those due to (iii) the thermal pulse-induced Brownian motion of particles.In a series of DEM simulations of sub-mi...

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“…In order to obtain a reasonable compromise between Table 2 The material parameters used in the numerical simulations (Roberts R. et al, 1994;Bharadwaj R. et al, 2010;Darelius A. et al, 2007;Li L. et al, 2015b) Variable Unit Value…”

Section: Generalmentioning

confidence: 99%

Effect of Drag Models on Residence Time Distributions of Particles in a Wurster Fluidized Bed: a DEM-CFD Study

Remmelgas

Wachem

et al. 2016

KONA

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Fluidized bed coating has been used to coat pellets or tablets with functional substances for a number of purposes. In this coating process, particle wetting, drying and film formation are coupled to particle motion. It is therefore of interest to study particle motion in such fluidized beds and to use the results to develop a model for predicting the quality of the final product. In this paper, we present results from DEM-CFD simulations, i.e. discrete element method and computational fluid dynamics simulations of particle motion in a laboratory-scale Wurster fluidized bed that was also employed in positron emission particle tracking (PEPT) experiments. As the drag force is the dominant interaction between the gas flow and the particle motion in this type of fluidized bed, the effect of drag models on the particle motion is investigated. More specifically, the particle velocity and residence time distributions of particles in different regions calculated from five different drag models are presented. It is found that the Gidaspow and Tang drag models predict both particle cycle and residence times well. The HKL and Beetstra drag models somewhat overestimate the particle velocity in the Wurster tube and therefore predict a reduced number of recirculations and a significantly shorter cycle time.

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The coefficient of restitution of some pharmaceutical tablets/compacts

Cited by 41 publications

References 24 publications

Experimental Analysis of Tablet Properties for Discrete Element Modeling of an Active Coating Process

Experimental Analysis of Tablet Properties for Discrete Element Modeling of an Active Coating Process

Improving Conductivity in Nano-Conduit Flows by Using Thermal Pulse-Induced Brownian Motion: A Spectral Impulse Intensity Approach

Effect of Drag Models on Residence Time Distributions of Particles in a Wurster Fluidized Bed: a DEM-CFD Study

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