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.

In this paper, we increase the understanding of the influence of the breathing pattern on the fate of inhaled non-spherical micro and nanoparticles and examine the accuracy of replacing the cyclic flow field with a quasi-steady flow. This is done with new analysis and numerical simulations on straight model airways using a previously developed discrete model for fiber motion. For the conditions studied, maximum deposition is obtained when fibers are released at the start of the inspiratory cycle, and minimum is received at the peak of inhalation. A quasi-steady solution generally provides a relatively good approximation to cyclic flow if an average velocity over one residence time of the particles moving with the mean fluid velocity is used. For a batch type, supply of particles deposition is favored in light activity breathing as compared to heavy breathing and the inclusion of a short pause after the inhalation results in an increased deposition in the terminal bronchiole. During zero-flow over the time of a breathing pause, spherical 10 nm particles experience considerable deposition in the distal airways, whereas only a few percent of larger and/ or fibrous nanoparticles were deposited. Hence, size and shape are crucial variables for deposition for no flow conditions. Common for all breathing parameters examined was that minimum deposition was obtained for the spherical 1 μm-particles and the fibrous 100 nm-particles. The former is expected from studies on spherical particles, and the latter is in agreement with results from a recent publication on steady inspiration.

A model for the motion and deposition of oblate and prolate spheroids in the nano-and microscale was developed. The aim was to mimic the environment of the human lung, but the model is general and can be applied for different flows and geometries for small nonspherical particle Stokes and Reynolds numbers. A study of the motion and orientation of a single oblate and prolate particle has been done yielding that Brownian motion disturbs the Jeffery orbits for small particles. Prolate microparticles still display distinguishable orbits while oblate particles of the same size do not. A statistical study was done comparing the deposition efficiencies of oblate and prolate spheroids of different size and aspect ratio observing that smaller particles have higher deposition rate for lower aspect ratio while larger particles have higher deposition rates for large aspect ratio.