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|Title: ||Direct simulation studies of suspended particles and fibre-filled suspensions|
|Authors: ||Joung, Clint Gwarngsoo|
|Keywords: ||direct simulation;fibre suspension;flexible fibres|
|Issue Date: ||2003|
|Publisher: ||University of Sydney. Chemical Engineering|
|Abstract: ||A new Direct Simulation ﬁbre model was developed which allowed ﬂexibility in the ﬁbre during the simulation of ﬁbre suspension ﬂow.This new model was called the 'Chain-of-Spheres' model.It was hypothesised that particle shape and deformation could signiﬁcantly aﬀect particle dynamics,and also suspension bulk properties such as viscosity.Data collected from the simulation showed that ﬂexible ﬁbres in shear ﬂow resulted in an order of 7 −10% bulk relative viscosity increase over the 'rigid' ﬁbre result.Results also established the existence of a relationship between bulk viscosity and particle stiﬀness. In comparison with experimental results,other more conventional rigid ﬁbre based methods appeared to underpredict relative viscosity.The ﬂexible ﬁbre method thus markedly improved the ability to estimate relative viscosity.The curved rigid ﬁbre suspension also exhibited increased viscosity of the order twice that of the equivalent straight rigid ﬁbre suspension.With such sensitivity to ﬁbre shape,this result has some important implications for the quality of ﬁbre inclusions used.For consistent viscosity,the shape quality of the ﬁbres was shown to be important. The 'Chain of Spheres' simulation was substantially extended to create a new simulation method with the ability to model the dynamics of arbitrarily shaped particles in the Newtonian ﬂow ﬁeld.This new '3D Particle' simulation method accounted for the inertial force on the particles,and also allowed particles to be embedded in complex ﬂow ﬁelds.This method was used to reproduce known dynamics for common particle shapes,and then to predict the unknown dynamics of various other particle shapes in shear ﬂow. In later sections, the simulation demonstrated inertia-induced particle migration in the non-linear shear gradient Couette cylinder ﬂow,and was used to predict the ﬁbre orientation within a diverging channel ﬂow.The performance of the method was veriﬁed against known experimental measurements,observations and theoretical and numerical results where available.The comparisons revealed that the current method reproduced single particle dynamics with great ﬁdelity. The broad aim of this research was to better understand the microstructural dynamics within the ﬁbre-ﬁlled suspension and from it,derive useful engineering information on the bulk ﬂow of these ﬂuids.This thesis represents a move forward to meet this broad aim.It is hoped that future researchers may beneﬁt from the new approaches and algorithms developed here.|
|Rights and Permissions: ||Copyright Joung, Clint Gwarngsoo;http://www.library.usyd.edu.au/copyright.html|
|Appears in Collections:||Sydney Digital Theses (Open Access)|
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