Direct numerical simulation and experimental validation of flow resistivity of nonwoven fabric filter

We numerically study and then experimentally validate the flow resistivity of commercial nonwoven fabric filters used for a bag filter system. To represent a realistic flow field inside the filters during simulation, a numerical method that coordinates the filter structure obtained by X-ray computed tomography imaging with computational fluid dynamics using the immersed boundary method is developed. The effects of superficial velocity, porosity of the filter domain, and type of filter on pressure drop are investigated and analyzed based on Darcy's law. The predictions from our numerical method are quantitatively in good agreement with the experimental measurements. We demonstrate that the Kozeny constants of the filters can be estimated by utilizing the solid volume fraction. These results demonstrate that our simulation method can be used to clarify the effects of porosity, fiber arrangement, and fiber shape on the pressure drop. Finally, its application to water droplet permeation is demonstrated.