Recommendations for simulating microparticle deposition at conditions similar to the upper airways with two-equation turbulence models

• Published in: Journal of aerosol science Vol. 119; pp. 31 - 50
• Main Authors: Bass, Karl, Worth Longest, P.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.05.2018
• Subjects: Aerosol deposition; Best practices; CFD modeling; Large eddy simulation (LES); Low Reynolds number (LRN) turbulence model; Meshing guidelines; Reynolds-averaged Navier Stokes (RANS) equations; Solution guidelines; Meshing guidelines; Reynolds-averaged Navier Stokes (RANS) equations; Solution guidelines; Low Reynolds number (LRN) turbulence model; CFD modeling; Aerosol deposition; Large eddy simulation (LES); Best practices; solution guidelines; aerosol deposition; meshing guidelines; best practices
• DOI: 10.1016/j.jaerosci.2018.02.007
• ISSN: 0021-8502

The development of a CFD model, from initial geometry to experimentally validated results with engineering insight, can be a time-consuming process that often requires several iterations of meshing and solver set-up. Applying a set of guidelines in the early stages can help to streamline the process and improve consistency between different models. The objective of this study was to determine both mesh and CFD solution parameters that enable the accurate simulation of microparticle deposition under flow conditions consistent with the upper respiratory airways including turbulent flow. A 90° bend geometry was used as a characteristic model that occurs throughout the airways and for which high-quality experimental aerosol deposition data is available in the transitional and turbulent flow regimes. Four meshes with varying degrees of near-wall resolution were compared, and key solver settings were applied to determine the parameters that minimize sensitivity to the near-wall (NW) mesh. The Low Reynolds number (LRN) k-ω model was used to resolve the turbulence field, which is a numerically efficient two-equation turbulence model, but has recently been considered overly simplistic. Some recent studies have used more complex turbulence models, such as Large Eddy Simulation (LES), to overcome the perceived weaknesses of two-equation models. Therefore, the secondary objective was to determine whether the more computationally efficient LRN k-ω model was capable of providing deposition results that were comparable to LES. Results show how NW mesh sensitivity is reduced through application of the Green-Gauss Node-based gradient discretization scheme and physically realistic near-wall corrections. Using the newly recommended meshing parameters and solution guidelines gives an excellent match to experimental data. Furthermore, deposition data from the LRN k-ω model compares favorably with LES results for the same characteristic geometry. In summary, this study provides a set of meshing and solution guidelines for simulating aerosol deposition in transitional and turbulent flows found in the upper respiratory airways using the numerically efficient LRN k-ω approach. [Display omitted] •Development and validation of CFD meshing/solution guidelines for aerosol deposition.•Sensitivity to near-wall mesh resolution is reduced with newly recommended parameters.•Numerical results compare well with experimental data for a characteristic geometry.•Computationally efficient LRN k-ω compares well with LES data for the same model.