Carbon nanoparticle-filled polymer flow in the fabrication of novel fiber composites Ahmed Elgafy a , Khalid Lafdi a,b, * a University of Dayton, 300 College Park, Dayton, OH 45469, USA b AFRL/MLBC, WPAFB, OH 45433, USA Received 29 April 2005; accepted 13 January 2006 Abstract During the fabrication process of advanced composites using nanoparticle-filled matrices, many problems potentially could arise. One such problem is the clogging of the channels of the microfiber matrix used due to strong interactions between the nanoparticle additives and the matrix walls. In the present paper, a two-dimensional simulation model based on an Eulerian multiphase flow approach is intro- duced to investigate and predict the flow characteristics of carbon nanoparticle-filled fluid around carbon microfiber matrix. The inter- actions between the microfiber matrix walls and the nanoparticle additives have been studied, and an energy ‘‘imbalance’’ technique has been applied between the fluid and the microfiber walls to prevent any potential sticking of the nanoparticle additives on the microfiber matrix walls during the flow process. The concept of phasic volume fractions is utilized, and the effects of external body forces, lift forces, and virtual mass forces are introduced into the momentum equations. The phase coupled SIMPLE algorithm is employed to solve the model. Ó 2006 Published by Elsevier Ltd. Keywords: Carbon nanoparticles; Impregnation; Modeling; Transport properties 1. Introduction New generation composites using nanoparticle-filled matrices have been significantly broadened to encompass a large variety of one, two, and three-dimensional systems made of distinctly dissimilar components mixed at the nanometer scale. This rapidly expanding field is generating many exciting new advanced composites by combining properties from the parent constituents into a single mate- rial. Besides achieving composites that have desirable prop- erties, there is also the possibility of gaining new properties, which are unknown in the parent constituent materials [1,2]. In particular, enhancing the thermal performance of fluids by using nanoparticle additives is considered as motivation for creating these composites [3–6]. The presence of the high thermal conducting nanoparticles in the fluids can increase the effective thermal conductivity of the fluid and conse- quently can enhance the heat transfer characteristics [5–11]. In addition to thermal properties, use of nanoparticle additives may enhance the mechanical properties of com- posites, and in theory, carbon nanoparticle additives could enhance both chemical and physical properties of compos- ites [12–15]. Moreover, the nanoparticle-filled fluids have a distinctive characteristic, which is quite different from those of traditional solid–liquid mixtures in which millimeter and/or micrometer-sized particles are involved. Large particles can create pressure drop due to settling effects. In contrast, the nanoparticle-filled fluids exhibits signifi- cantly less additional pressure drop when flowing through the passages [3]. Nevertheless, the possibility of clogging micrometric channels remains a challenge, but instead of settling to gravity, settling due to the ‘‘sticking’’ of particles to the surface is the issue. For instance, this issue is 0008-6223/$ - see front matter Ó 2006 Published by Elsevier Ltd. doi:10.1016/j.carbon.2006.01.029 * Corresponding author. Address: University of Dayton, 300 College Park, Dayton, OH 45469, USA. Tel.: +1 937 229 4797; fax: +1 937 229 3433. E-mail address: Lafdi@udri.udayton.edu (K. Lafdi). www.elsevier.com/locate/carbon Carbon 44 (2006) 1682–1689