@article{jaganathan_tafreshi_pourdeyhimi_2009, title={A realistic modeling of fluid infiltration in thin fibrous sheets}, volume={105}, ISSN={["1089-7550"]}, DOI={10.1063/1.3141737}, abstractNote={In this paper, a modeling study is presented to simulate the fluid infiltration in fibrous media. The Richards’ equation of two-phase flow in porous media is used here to model the fluid absorption in unsaturated/partially saturated fibrous thin sheets. The required consecutive equations, relative permeability, and capillary pressure as functions of medium’s saturation are obtained via fiber-level modeling and a long-column experiment, respectively. Our relative permeability calculations are based on solving the Stokes flow equations in partially saturated three-dimensional domains obtained by imaging the sheets’ microstructures. The Richards’ equation, together with the above consecutive correlations, is solved for fibrous media inclined with different angles. Simulation results are obtained for three different cases of upward, horizontal, and downward infiltrations. We also compared our numerical results with those of our long-column experiment and observed a good agreement. Moreover, we establish empirical coefficients for the semianalytical correlations previously proposed in the literature for the case of horizontal and downward infiltrations in thin fibrous sheets.}, number={11}, journal={JOURNAL OF APPLIED PHYSICS}, author={Jaganathan, Sudhakar and Tafreshi, Hooman Vahedi and Pourdeyhimi, Behnam}, year={2009}, month={Jun} }
 @article{jaganathan_tafreshi_shim_pourdeyhimi_2009, title={A study on compression-induced morphological changes of nonwoven fibrous materials}, volume={337}, ISSN={["1873-4359"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-59349102148&partnerID=MN8TOARS}, DOI={10.1016/j.colsurfa.2008.12.019}, abstractNote={Pore size is a characteristic parameter that is often defined for fibrous materials used in industrial applications. While there exist many available studies on the pore size distribution of different fibrous materials, the influence of compression load on pore size distribution has not been studied well. Studying the behavior of fibrous materials under compression is important especially because in many applications these materials are subjected to some degree of compression during use. In this work, we present a novel image-based modeling technique to study the changes in the pore size distribution of a fibrous material exposed to compressive load. This was made possible by building a miniature compression cell, and imaging the structure of a hydroentangled fabric under varying levels of compression. The 3D images obtained with Digital Volumetric Imaging were utilized to study the pore size distribution of the material and develop an empirical correlation as a function of compressive stress for these structures. This new correlation indicates that the mean pore diameter of a nonwoven material decreases exponentially with increasing the compressive stress.}, number={1-3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Jaganathan, S. and Tafreshi, H. Vahedi and Shim, E. and Pourdeyhimi, B.}, year={2009}, month={Apr}, pages={173–179} }
 @article{tafreshi_rahman_jaganathan_wang_pourdeyhimi_2009, title={Analytical expressions for predicting permeability of bimodal fibrous porous media}, volume={64}, ISSN={["0009-2509"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-59349120565&partnerID=MN8TOARS}, DOI={10.1016/j.ces.2008.11.013}, abstractNote={Pressure drop is one of the most important characteristics of a fibrous media. While numerous analytical, numerical, and experimental published works are available for predicting the permeability of media made up of fibers with a unimodal fiber diameter distribution (referred to as unimodal media here), there are almost no easy-to-use expressions available for media with a bimodal fiber diameter distribution (referred to as bimodal media). In the present work, the permeability of bimodal media is calculated by solving the Stokes flow governing equations in a series of 3-D virtual geometries that mimic the microstructure of fibrous materials. These simulations are designed to establish a unimodal equivalent diameter for the bimodal media thereby taking advantage of the existing expressions of unimodal materials for permeability prediction. We evaluated eight different methods of defining an equivalent diameter for bimodal media and concluded that the area-weighted average diameter of Brown and Thorpe [2001. Glass-fiber filters with bimodal fiber size distributions. Powder Technology 118, 3–9], volume-weighted resistivity model of Clague and Phillips [1997. A numerical calculation of the hydraulic permeability of three dimensional disordered fibrous media. Physics of Fluids 9 (6), 1562–1572], and the cube root relation of the current paper offer the best predictions for the entire range of mass (number) fractions, 0⩽nc⩽1, with fiber diameter ratios, 1⩽Rcf⩽5, and solidities, 5⩽α⩽15.}, number={6}, journal={CHEMICAL ENGINEERING SCIENCE}, author={Tafreshi, H. Vahedi and Rahman, M. S. A. and Jaganathan, S. and Wang, Q. and Pourdeyhimi, B.}, year={2009}, month={Mar}, pages={1154–1159} }
 @article{jaganathan_vahedi tafreshi_pourdeyhimi_2008, title={Modeling liquid porosimetry in modeled and imaged 3-D fibrous microstructures}, volume={326}, ISSN={0021-9797}, url={http://dx.doi.org/10.1016/j.jcis.2008.07.011}, DOI={10.1016/j.jcis.2008.07.011}, abstractNote={In this paper, an analysis to distinguish the geometric and porosimetric pore size distributions of a fibrous material is presented. The work is based on simulating the intrusion of nonwetting fluid in a series of 3-D fibrous microstructures obtained from 3-D image reconstruction or virtual geometries mathematically generated according to the properties of the media. We start our study by computing the pore size distribution of two typical hydroentangled nonwoven materials and present a theoretical model for their geometric pore size distributions based on Poisson line network model of the fibrous media. It is shown that the probability density function of the geometric pore size distribution can be approximated by a two-parametric Gamma distribution. We also study connectivity of the pore space in fibrous media by computing and comparing the accessible and allowed pore volumes in the form access function graphs. It is shown that the so-called ink-bottle effect can significantly influence the fluid intrusion in a porous material. The pore space connectivity of a homogeneous fibrous media is observed to be a function of thickness, solid volume fraction (SVF), and fiber diameter. It is shown that increasing the materials' thickness or SVF, while other properties are kept constant, reduces the pore space connectivity. On the other hand, increasing the fiber diameter enhances the connectivity of the pores if all other parameters are fixed. Moreover, modeling layered fibrous microstructures; it is shown that the access function graphs can be used to detect the location of the bottle neck pores in a layered/composite porous material.}, number={1}, journal={Journal of Colloid and Interface Science}, publisher={Elsevier BV}, author={Jaganathan, S. and Vahedi Tafreshi, H. and Pourdeyhimi, B.}, year={2008}, month={Oct}, pages={166–175} }
 @article{jaganathan_tafreshi_pourdeyhimi_2008, title={On the pressure drop prediction of filter media composed of fibers with bimodal diameter distributions}, volume={181}, ISSN={["1873-328X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-37849049035&partnerID=MN8TOARS}, DOI={10.1016/j.powtec.2007.07.002}, abstractNote={In addition to collection efficiency, pressure drop is the most important characteristic of a filter medium. While there are numerous analytical expressions available for predicting the pressure drop of the filters made up of fibers with a unimodal fiber diameter distribution, there are not enough studies dedicated to filters composed of fibers with a bimodal (or multimodal) fiber diameter distribution. In this work, the pressure drop per unit thickness of filters made of bimodal fiber diameters is calculated by solving the Navier–Stokes equations in a series of 2-D geometries. These results are used to find the unimodal equivalent diameters of each bimodal filter that could be used in the existing expressions for calculating pressure drop. In agreement with the work of Brown and Thorpe [Brown, R.C., Thorpe, A., Glass-fiber filters with bimodal fiber size distributions. Powder Technology 118 (2001) 3–9.], it was found that the area-weighted averaging of the fiber diameters in a bimodal filter provides a relatively good estimation of its equivalent unimodal fiber diameter. We, however, noticed that in such an averaging the error percentage in the pressure drop prediction is sensitive to the fiber diameter ratios as well as the fraction of each fiber diameter in the bimodal filter. We, therefore, obtained a correction factor for the estimation of the unimodal equivalent diameters as a function of fiber diameter ratio and their number fractions.}, number={1}, journal={POWDER TECHNOLOGY}, author={Jaganathan, S. and Tafreshi, H. Vahedi and Pourdeyhimi, B.}, year={2008}, month={Jan}, pages={89–95} }
 @article{jaganathan_maze_tafreshi_pourdeyhimi_2008, title={Simulating Liquid Flow through Virtual Glass Fiber Mats}, volume={78}, ISSN={["1746-7748"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-52949145262&partnerID=MN8TOARS}, DOI={10.1177/0040517507085195}, abstractNote={ The focus of this paper is on simulating the in-plane and through-plane penetration of liquid water in virtual non-wovens. We consider a series of unsteady state two-phase (air—water) simulations performed in two-dimensional geometries obtained from a simulated three-dimensional glass fiber mat. The simulation planes are the cross-sectional planes in the horizontal and vertical directions. Simulations revealed that liquid penetration and spread depend strongly on the fiber orientation distribution as well as on the hydrophilic properties of the fibers. Our results are in good qualitative agreement with the available experimental data. }, number={10}, journal={TEXTILE RESEARCH JOURNAL}, author={Jaganathan, S. and Maze, B. and Tafreshi, H. Vahedi and Pourdeyhimi, B.}, year={2008}, month={Oct}, pages={903–910} }
 @article{jaganathan_tafreshi_pourdeyhimi_2008, title={The influence of forming surface on the vacuum pressure in hydroentangling process}, volume={99}, ISSN={["1754-2340"]}, DOI={10.1080/00405000701692338}, abstractNote={Hydroentangling is a process that uses waterjet curtains issued from a series of parallel jet-heads (manifolds) for entangling and interloping fibres in a loose fibre web carried on a belt or perforated surface. The efficient removal of the stagnant water remaining from each waterjet curtain is crucial for the success of fibre entanglement when the web reaches the next jet-head. In this article, we discuss different methodologies that can be used to calculate the minimum vacuum pressure required for extracting the hydroentangling water from non-woven fabrics. A distinction has been made between hydroentangling on tightly and openly woven screens and different modelling strategies are recommended for each. In particular, it is demonstrated that a one-dimensional flow pattern coupled with available analytical permeability expressions can be used to predict the required vacuum pressure in the case of tightly woven screens. In the case of open woven screens where the flow pattern becomes three-dimensional, numerical simulation is needed for calculating the vacuum pressure required for complete removal of hydroentangling water. We also demonstrated that the vacuum pressure increases by decreasing the fibre diameter or increasing the fabrics' solid volume fractions.}, number={5}, journal={JOURNAL OF THE TEXTILE INSTITUTE}, author={Jaganathan, S. and Tafreshi, H. Vahedi and Pourdeyhimi, B.}, year={2008}, pages={407–414} }