Investigation of accumulation of particles into fibrous filters using x-ray tomography and flow simulations

Filtration mechanisms have been studied for decades with direct filtration experiments, theoretical analysis and more recently by computer simulations. Moreover, modern imaging techniques like X-ray microtomography enable microscopic structural analysis of clean and dirty filters, and the obtained 3D images can be used after binarization for realistic filtration simulations. As the underlying physical mechanisms in filtering are very complicated, the development of new types of filters is hardly possible without combining these different approaches.
In this work, we combine filtration experiments, X-ray microtomographic imaging and realistic filtration simulations for the analysis of filters and filtering. To this end, we study the filtration properties of two industrial filters and a generic test filter made from a mixture of viscose fibres and softwood pulp by foam forming. The filtration efficiency of these filters is measured and the filters are then loaded with fine test dust. The filters are imaged before and after loading with X-ray microtomography. The 3D structure of the clean filters and the spatial distribution of the dust particles in the loaded filters is analyzed. Moreover, accumulation of particles is simulated based on latticeBoltzmann flow simulations, and the obtained simulated spatial distributions of the particles are compared with the measured distributions.