@article{bhatta_gautam_farhan_tafreshi_pourdeyhimi_2024, title={Accuracy of the Pore Morphology Method in Modeling Fluid Saturation in 3D Fibrous Domains}, volume={10}, ISSN={["1520-5045"]}, url={https://doi.org/10.1021/acs.iecr.4c02939}, DOI={10.1021/acs.iecr.4c02939}, abstractNote={The volume-of-fluid (VOF) method is among the most popular methods of simulating fluid saturation in porous media. Unfortunately, however, the VOF method becomes extremely slow in 3D domains. The problem arises from the need to use very small time steps and volume elements to achieve an accurate and stable numerical simulation. A quasi-static alternative to approximate the results of VOF simulations is the pore morphology method (PMM). The PMM does not require solving nonlinear partial differential equations (i.e., the Navier–Stokes equations), and as such, it is orders of magnitude faster than the VOF method in terms of CPU time. However, the PMM is less accurate than the VOF or other physics-based methods. The current study was therefore devised to assess the accuracy of PMM simulations in geometries with different degrees of anisotropy and disorder. Our study revealed that the PMM predictions become inaccurate when the pores in the media have high-aspect-ratio cross sections (e.g., rectangular cross sections). It was also found that the PMM algorithm marks the largest pore in the domain as the location where a non-wetting phase starts penetrating into the saturated media regardless of the contact angle of the media (as long as all solid surfaces in the media have the same contact angle), which obviously is inaccurate. The PMM results reported in this paper were produced by using an in-house MATLAB code.}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Bhatta, Nishant and Gautam, Sashank and Farhan, Noor M. and Tafreshi, Hooman V. and Pourdeyhimi, Behnam}, year={2024}, month={Oct} }
 @article{bhatta_tafreshi_pourdeyhimi_2024, title={Toward formulating coalescence filtration: Characterizing wetting saturation via centrifugal force}, volume={170}, ISSN={["1879-3533"]}, url={https://doi.org/10.1016/j.ijmultiphaseflow.2023.104641}, DOI={10.1016/j.ijmultiphaseflow.2023.104641}, abstractNote={Coalescence filtration is the removal of dispersed droplets from a gas or from an immiscible liquid using a fibrous filter. Coalescing filters operate under a partially-saturated condition where some of the filter pores are filled with accumulated droplets. To date, there exists no theory that can predict the filtration efficiency of a coalescing filter and this is due to the complicated coupling between the aerodynamic field inside the filter and the capillarity of the fibers. This paper presents a new approach to study coalescence filtration by replacing the aerodynamic field inside the filter with a centrifugal force field and to thereby decouple the role of fiber properties from that of the airflow in fluid accumulation in a filter. This paper is only the first step towards developing the above mathematical theory for coalescence filtration. In the current study, we use numerical simulation and experiment to compare desaturation of a liquid-saturated fibrous media via centrifugal force (new) and via compressed air (traditional). For the simulations, we used the volume-of-fluid (VOF) method implemented in ANSYS software, and for the experiments, we used a Porometer for the pressure-driven desaturation, and a custom-made setup inside a swing-bucket centrifuge for the centrifugal desaturation. The experiments were conducted using a nonwoven fabric infused with mineral oil. Pressure-driven and centrifugal desaturation processes were compared with one another, and the advantages of the latter were discussed in detail.}, journal={INTERNATIONAL JOURNAL OF MULTIPHASE FLOW}, author={Bhatta, Nishant and Tafreshi, Hooman V. and Pourdeyhimi, Behnam}, year={2024}, month={Jan} }