Thanasis D. Papathanasiou
Associate Professor
1. Stokes Flow across Unidirectional Disordered Fiber Arrays
The objective of many hundreds of such computations is to develop correlations which relate the permeability of unidirectional fibrous media to their microstructure. This involves differentiating between various hard-core arrays (currently lumped together under the heading "random") as well as identifying the exact point in microstructure evolution at which a fibrous medium's resistance to flow is significantly affected by clustering. A large part of this effort involves proposing and testing microstructural metrics that correlate with the observed trends in permeability.
Figure 1: Speed contours of creeping flow across unidirectional fiber arrays assuming regular (upper left), hard-core (upper right and lower left) and clustered (lower right) spatial distributions. The computations were carried out using an in-house boundary element code [X. Chen, PhD Thesis, 2005].
Figure 2: Speed contour during creeping flow across a disordered unidirectional fiber array consisting of 900 individual filaments. The simulation was carried out on Loslobos (an IBM cluster) at the High Performance Computing Center at the University of New Mexico, using a parallel version of an in-house boundary element code. This research is currently co-sponsored by NSF/DMII and by DOE/Automotive Lightweight Materials program.
2. Stress Distribution in Transversely Loaded Continuous Fiber Composites
Figure 3: Contours of first principal stress in transversely loaded continuous fiber composites Uniform tensile loading is applied in the horizontal direction.
Notice the difference between the stress distribution in a square array (left) and the stress distribution in an otherwise identical (in terms of constituent properties and ratios) hard-core array (right). This research is motivated by the need to quantify the stress enhancement caused by microstructural variations and correlate it to quantitative measures of the composite microstructure. (X. Chen and T. D. Papathanasiou, 2004).
3. A Master Curve for Permeability of Structured Dual-Porous Fibrous Assembly
Figure 4: A large number of simulations in geometries describing deterministic dual porosity fibrous media has revealed a relationship between the geometry of the medium (expressed by Ks and Ktow in the above equation) and the permeability of the overall medium (Kp) [T. D. Papathanasiou, 2001].
