Simulation of Particulate Matter Structure Detachment from Surfaces of Wall-Flow Filters for Elevated Velocities Applying Lattice Boltzmann Methods
Round 1
Reviewer 1 Report
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Comments for author File: 
Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
In this work, the authors conducted a numerical study on the particulate matter structure detachment from the surfaces of wall-flow filters for elevated velocity where the homogenized lattice Boltzmann method is applied. They focused on the quantification of the stability and accuracy, the hydrodynamic surface forces, and also reported some interesting results. The manuscript can be accepted provided the following issues are addressed.
-Abstract: lattice Boltzmann method approach-> lattice Boltzmann method
-Page 3: particle-free and particle-including flow-> particle-free and particle-including flows
-The lattice BGK model is adopted in this work, while it may be unstable when the relaxation time is close to 0.5. Can the authors consider a more advanced multiple-relaxation-time lattice Boltzmann method (MRT-LBM)? Actually, the lattice BGK model is only a special case of the MRT-LBM, and the MRT-LBM can be more stable and more accurate than the lattice BGK model through adjusting the free relaxation parameters properly (Phys. Rev. E 83, 056710 (2011); Phys. Rev. E 102, 023306 (2020)).
-To the reviewer’s knowledge, some researchers developed a diffuse-interface LBM, as an improved form of the partially saturated method (PSM) (Comput. Fluids 233, 105240 (2022)), for fluid-solid interaction problems. In this work, the so-called homogenized lattice Boltzmann method (HLBM) represented as a specific form of PSM is adopted, now the question is what is the difference among these three methods, please give some discussion on this issue.
-The authors conducted a study on the convergence rate of the numerical method, while additionally, it may be better to perform a grid-independence test for a specific case before performing any simulations.
Author Response
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Reviewer 3 Report
Summary
The main contributions of the paper include:
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A comprehensive quantification of stability and accuracy of particle-free and particle-including flow, considering static, impermeable deposition layer fragments.
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Determination of the hydrodynamic surface forces and the deduction of the local detachment likelihood of individual layer fragments.
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Identification of the suitable parameter domain for the flow around a single layer fragment, attached to the porous wall's substrate, and determination of the relevant force for the prediction of fragment detachment.
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Derivation of predictions on the detachment likelihood of individual layer fragments and their mutual influence based on the spatial distribution of hydrodynamic forces.
The paper's strengths lie in its use of a lattice Boltzmann method approach and its investigation of elevated velocities of up to 60 m/s, which contributes to an understanding of rearrangement events and respective deposition pattern predictions. The paper's findings have potential implications for optimizing engine performance, fuel consumption, and service life of wall-flow filters.
Overall, I recommend publishing with minor modifications.
General concept comments
I hope the authors can respond to the following general concerns about the methods used and results presented in the manuscript:
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The paper uses several simplifying assumptions in the mathematical model, such as
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assuming the fluid is incompressible
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neglecting thermal effects
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neglecting chemical reactions and electrostatic forces that may affect particle deposition or detachment
Do these assumptions hold true in real-world scenarios? If not, how would they affect the results?
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The paper does not describe any experimental validation of the simulation results. Although the simulation results may be consistent with theoretical expectations, experimental validation is important to confirm the accuracy of the mathematical model and numerical methods used. Have the authors validated the simulation results with any experimental data?
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The mathematical model used in the paper is complex and requires a significant amount of computational resources to simulate. This complexity may limit the scalability of the model to larger systems and longer timescales. Can the authors provide more details of the computation resources utilized in the study and comment on if this model is applicable to real-world applications?
Specific comments
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Figure 1: a transparent view of the channel model could be more illustrative.
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Figure 7: how is “distance to theoretic LBM stability limit” derived? how does the computation cost change with increasing N? how does the “practical” LBM stability limit look if you’re constrained by computation resources?
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Figure 9: using lines of different thicknesses to represent velocity in and velocity out can be confusing to readers, can you use different line styles or markers to make them more distinguishable? How does the velocity and pressure profile look like in the y-z plane?
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Figure 11: the simulation times out at a velocity of 25 m/s for N>=96 but the theoretic LBM stability limit (green area) indicated by the figure is way higher than that, can you please explain?
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Figure 18: Can you also report the velocity & pressure profile similar to Figure 9 to complement the 3D flow field?
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Line 333-335: why choose tmax=0.1s as the maximum simulation time to determine timeout?
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Line 341-342: it seems confusing to say “for a resolution of N = 48 and above, inflow
velocities up to 20 m s−1 can be realized” because the velocity limit is higher for larger N. Is 20m s-1 the lower limit?
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Line 431-433: does it imply that the velocity profile of this application use is similar to what’s reported in Figure 9?
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
