The objective of this study is to well understand the migration and orientation of thin micro-particles in a suspension flow by means of both experiments and numerical simulations. In this framework, the evolution of the orientation of thin micro-particles such as talc and mica, which were modeled by a disk-like particle, in a flow through a slit channel was analyzed to obtain the knowledge of the processing operations of thin micro-particle reinforced composites.
The thin disk-like particles were subjected by a planar extensional flow in a reservoir, then by a simple shear flow through a slit channel in the experimental apparatus used. The evolution of the orientation of thin disk-like particles was, therefore, studied in both a planar extensional and simple shear flows by numerical calculation of the Jeffery equation: thin disk-like particles aligned in a parallel orientation to upper- and lower-walls of the slit channel in a planar extensional flow through the reservoir, then entered into the inlet of the slit channel. On the other hand, in a simple shear flow through the slit channel, the disk-like particles kept this parallel orientation except the occurrence of a flip-over phenomenon. The period of the flip-over became longer with a decrease in the aspect ratio of the disk-like particles.
Furthermore, the measurements of the orientation of the talc particles in a suspension flow through the slit channel clearly showed that almost the same period of the flip-over was found although the particle size was different. These experimental results arise from complex geometries and no accurate data of the thickness of the talc particles.

View full abstract

This paper describes two spectroscopic methods for measurement of soil adhered from the human body on the fabrics. Fourier transform infrared spectroscopy (FT-IR) was applied. Attenuated total reflectance spectra and diffuse reflectance spectra were measured. The partial least squares regression calibration models were obtained by using the model soils that were prepared. These methods were applied to measure the real soil from the human body on the fabrics. The rapid and non-destructive measurement of the soil on the fabrics could be proposed based on these methods.

View full abstract