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Comparing mesh-based and voxel-based CFD models for aerosol deposition in complex fibrous filters

Authors:

Abstract

Today, liquid aerosols are generated in many industrial processes like machining, manufacturing of catalysts or in pneumatic compressors. Liquid aerosols may be harmful since small droplet may enter the respiratory system and cause lung cancer, allergies, or other diseases. Also, due to the recent COVID-19 outbreak, aerosols containing viruses are classified as dangerous. We present results of micro-scale simulations of mist deposition on fibrous structures and validate them by comparison to single fiber efficiency (SFE) theory and to experimental data. An Eulerian-Lagrangian CFD model for liquid aerosol deposition on clean fibrous filter media was developed in a mesh-based code (StarCCM+) and a voxel-based code (GeoDict). The CFD codes consider the filtration due to impaction, interception and diffusion. For validation purposes, a single fiber efficiency (SFE) simulation was build up. The SFE-model is a simple filtration system, which contains only one single straight fiber, see Mead Hunter et al. [1]. Based on high-resolution µCT scans both codes were applied to a real fibrous filter structure to determine both fractional filtration efficiency and pressure drop of the scanned filter section. The results extrapolated to the whole filter are found to be in good agreement with experimental measurements. While the results of the mesh-based code are slightly closer to the experimental results, the computational time of the voxel-based code is orders of magnitude faster than that of the mesh-based code. However, it needs to be stressed that this comparison includes uncertainties due to possible heterogeneities of the real filter and due to the extrapolation step.
Comparing mesh-based and voxel-based CFD models for aerosol
deposition in complex fibrous filters
Dennis Hoch1, Mehdi Azimian2, André Baumann1, Jens Behringer1, Jennifer
Niessner1
1Institute for Flow in Additively Manufactured Porous Media (ISAPS), Heilbronn
University of Applied Sciences, Germany, 2Math2Market GmbH, Richard-Wagner-Str.
1, 67655 Kaiserslautern, Germany, dennis.hoch@hs-heilbronn.de
Today, liquid aerosols are generated in many industrial processes like machining,
manufacturing of catalysts or in pneumatic compressors. Liquid aerosols may be
harmful since small droplet may enter the respiratory system and cause lung cancer,
allergies, or other diseases. Also, due to the recent COVID-19 outbreak, aerosols
containing viruses are classified as dangerous. We present results of micro-scale
simulations of mist deposition on fibrous structures and validate them by comparison
to single fiber efficiency (SFE) theory and to experimental data.
An Eulerian-Lagrangian CFD model for liquid aerosol deposition on clean fibrous filter
media was developed in a mesh-based code (StarCCM+) and a voxel-based code
(GeoDict). The CFD codes consider the filtration due to impaction, interception and
diffusion. For validation purposes, a single fiber efficiency (SFE) simulation was build
up. The SFE-model is a simple filtration system, which contains only one single straight
fiber, see Mead Hunter et al. [1].
Based on high-resolution µCT scans both codes were applied to a real fibrous filter
structure to determine both fractional filtration efficiency and pressure drop of the
scanned filter section. The results extrapolated to the whole filter are found to be in
good agreement with experimental measurements. While the results of the mesh-
based code are slightly closer to the experimental results, the computational time of
the voxel-based code is orders of magnitude faster than that of the mesh-based code.
However, it needs to be stressed that this comparison includes uncertainties due to
possible heterogeneities of the real filter and due to the extrapolation step.
References:
[1] R. Mead-Hunter, A.J.C. King, G. Kasper, B. J. Mullins, Journal of Aerosol Science 2013, 61, 3649.
Left: Pressure distribution in the filter section obtained by GeoDict. Right: Collected droplets on the fibers
obtained by GeoDict after 220 ms.
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Left: Pressure distribution in the filter section obtained by GeoDict
  • R Mead-Hunter
  • A J C King
  • G Kasper
  • B J Mullins
R. Mead-Hunter, A.J.C. King, G. Kasper, B. J. Mullins, Journal of Aerosol Science 2013, 61, 36-49. Left: Pressure distribution in the filter section obtained by GeoDict. Right: Collected droplets on the fibers obtained by GeoDict after 220 ms.