Development of scientifically engineered fibrous porous networks has been gaining momentum due to their potential advantages in a wide spectrum of end-uses. Behavior of fluid flow through fibrous networks is the determinant factor in engineering design of these materials for applications in various manufacturing and process industries. Precise definition of traort properties of fibrous porous networks entails greater understanding of their internal structure at micro-scale level. Thus, in this work using CFD simulation technique, the behavior of fluid flow in simulated images of needled nonwoven fabrics was investigated. Results were compared with available published empirical, analytical and numerical models. Comparison of the results were also made with the micro-computed tomography-based hybrid model of Soltani et al. It was found that the obtained results are in acceptable agreement with previously published findings. Using 3D simulated images of fibrous networks, behavior of fluid flow at micro-structure level was investigated. The 3D simulated images were prepared using sets of fiber networks with various degrees of fiber alignment including isotropic, layered and unidirectional. The in-plane and transverse permeability of the simulated structures were determined by solving the Stokes equations. It was found that permeability increases with increase in porosity and this variation was found to be non-linear. It was established that fibrous structures with marked fiber orientation in direction of the fluid flow, exhibit higher transverse permeability. Results revealed that increase in the angle between fiber axis and direction of the flow tends to reduce permeability. The amount of permeability due to the increase in the angle reduces in descending order in parallel to unidirectional networks, in parallel to layered networks, in isotropic networks, in flow perpendicular to layered networks and in ?ow perpendicular to unidirectional networks. Key Words: Needled nonwoven Fabric, Fluid flow simulation, Permeability, 3D fiber orientation, Porosity
