Modelling transport and deposition of non-spherical micro- and nano-particles in composites manufacturing

Abstract

In liquid moulding processes, a fabric is impregnated with a fluid that may contain particles aimed at giving the final product additional and possible smart properties. It is therefore interesting to be able to reveal how the distribution and orientation of such particles are affected by the processing condition. During the manufacturing of the fabric, relatively large channels are formed between bundles of fibres where the impregnating fluid may flow. There are also micro-channels within the bundle that are impregnated by the fluid in the larger channels mainly by capillary action. With focus on fibre bundles along the main flow direction, three main stages of the flow are the flow is leading within the bundles, the flow is moving at equal rate within the bundles and between them and the flow is leading in the channels between the bundles. The latter one of these is in focus in this study, and the capillary action from the larger channels to the micro-channels is modelled as a constant radial velocity. Brownian, gravitational and hydrodynamic forces acting on the particles are studied. The introduction of a radial velocity component drastically increases the deposition rate, and it is clear that while particle shape has a great influence on deposition rates in a flow moving strictly in the direction of the channel, when a radial flow component is introduced the differences seem to disappear.

Transport and Deposition of Large Aspect Ratio Prolate and Oblate Spheroidal Nanoparticles in Cross Flow

“…The purpose of the present work is to develop a theory for the transport of non-spherical nano-sized particles in cross-flow geometry using the Fokker-Planck approach and with an application to the flow configuration considered in the work of reference [3]. It extends and corrects some of the results of that paper.…”

“…The Lagrangian tracking method has recently also been used in a study of transport and deposition of non-spherical micro-and nano-particles related to composites manufacturing (Holmstedt et al [3]). During manufacturing micro-and nanoscale particles may be added to the resin to give the final product additional properties.…”

“…The effect from the porous media is then to provide a radial suction flow out from the tube. In the study in reference [3] it is assumed that all particles deposit when they reach the border between the channel and the annular fiber bundle. The amount of deposition found therefore denotes which particles are transported to the bundles and can be seen as the maximum possible deposition.…”

“…Although the geometry in focus in this work originally mimicked composite manufacturing, Holmstedt et al [3] the simplified geometry, with flow in a tube surrounded by a membrane porous medium, is perhaps more relevant in connection to cross-flow filtration techniques mentioned above. In cross-flow, filtration particles and fluid stream tangential in the axial direction of a tube, while in To the left: Intra-bundle channels, with gaps formed between individual fibers.…”

“…Although the geometry in focus in this work originally mimicked composite manufacturing, Holmstedt et al [3] the simplified geometry, with flow in a tube surrounded by a membrane porous medium, is perhaps more relevant in connection to cross-flow filtration techniques mentioned above.…”