Effective gas diffusion coefficient in fibrous materials by mesoscopic modeling

He, Xinting; Guo, Yangyu; Li, Min; Pan, Ning; Wang, Moran

doi:10.1016/j.ijheatmasstransfer.2016.11.097

Cited by 34 publications

(19 citation statements)

References 42 publications

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“…However, our correlation differs very strongly from the correlation for random orientated overlapping fibers proposed by He et al (2017). For low porosities, the correlation of He et al (2017) proposes effective diffusion factors larger than 1, which is physically unreasonable. It has to be mentioned that our law might slightly underestimate the diffusivity through filamentous fungal networks, because Figure 5 implies that the convergence might not be fully developed for a resolution of 13 voxels.…”

Section: Resultscontrasting

confidence: 99%

Universal law for diffusive mass transport through mycelial networks

Schmideder

Müller

Barthel

et al. 2020

Biotech & Bioengineering

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Filamentous fungal cell factories play a pivotal role in biotechnology and circular economy. Hyphal growth and macroscopic morphology are critical for product titers; however, these are difficult to control and predict. Usually pellets, which are dense networks of branched hyphae, are formed during industrial cultivations. They are nutrient‐ and oxygen‐depleted in their core due to limited diffusive mass transport, which compromises productivity of bioprocesses. Here, we demonstrate that a generalized law for diffusive mass transport exists for filamentous fungal pellets. Diffusion computations were conducted based on three‐dimensional X‐ray microtomography measurements of 66 pellets originating from four industrially exploited filamentous fungi and based on 3125 Monte Carlo simulated pellets. Our data show that the diffusion hindrance factor follows a scaling law with respect to the solid hyphal fraction. This law can be harnessed to predict diffusion of nutrients, oxygen, and secreted metabolites in any filamentous pellets and will thus advance the rational design of pellet morphologies on genetic and process levels.

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Section: Resultscontrasting

confidence: 99%

Universal law for diffusive mass transport through mycelial networks

Schmideder

Müller

Barthel

et al. 2020

Biotech & Bioengineering

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“…The correlations for 3D random distributed overlapping fibers (Figure b) fitted our data better than the correlations existing for filamentous microorganisms. Our data fall in between the correlation of Tomadakis and Sotirchos () and He et al (). In both studies, the computation of the effective diffusivity was well validated for other structures like parallel fibers.…”

Section: Resultssupporting

confidence: 88%

“…According to Nam and Kaviany (), the effective diffusivity of isotropic structures is often estimated using a power function of porosity. Thus, He et al () fitted their diffusion results of 3D random distributed overlapping fibers and found

k_{e f f} = α ϵ^{n}

, with

α = 1.05

and

n = 3

.…”

Section: Resultsmentioning

confidence: 97%

“…In the materials science of fibers, correlations between the porosity and the effective diffusion factor for bulk diffusion that include knowledge about the tortuosity have been described. Perrins, McKenzie, and McPhedran () derived an analytic expression for ideal square arrays of parallel fibers, Tomadakis and Sotirchos () a correlation for random distributed overlapping parallel fibers, Tomadakis and Sotirchos () and Tomadakis and Robertson () a relation for random distributed nonoverlapping parallel fibers, Tomadakis and Sotirchos () and He, Guo, Li, Pan, and Wang () a relation for 3D random distributed overlapping fibers, and Vignoles, Coindreau, Ahmadi, and Bernard () a correlation for parallel fibrous carbon–carbon composite preforms (Table ). The only published experimental approach to predict the diffusive mass transport is based on the measurement of oxygen concentrations using microelectrodes inside fungal pellets (Hille, Neu, Hempel, & Horn, ; Wittier, Baumgartl, Lübbers, & Schügerl, ).…”

Section: Introductionmentioning

confidence: 99%

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From three‐dimensional morphology to effective diffusivity in filamentous fungal pellets

Schmideder

Barthel

Müller

et al. 2019

Biotech & Bioengineering

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Filamentous fungi are exploited as cell factories in biotechnology for the production of proteins, organic acids, and natural products. Hereby, fungal macromorphologies adopted during submerged cultivations in bioreactors strongly impact the productivity. In particular, fungal pellets are known to limit the diffusivity of oxygen, substrates, and products. To investigate the spatial distribution of substances inside fungal pellets, the diffusive mass transport must be locally resolved. In this study, we present a new approach to obtain the effective diffusivity in a fungal pellet based on its three-dimensional morphology. Freeze-dried Aspergillus niger pellets were studied by X-ray microcomputed tomography, and the results were reconstructed to obtain three-dimensional images. After processing these images, representative cubes of the pellets were subjected to diffusion computations. The effective diffusion factor and the tortuosity of each cube were calculated using the software GeoDict. Afterwards, the effective diffusion factor was correlated with the amount of hyphal material inside the cubes (hyphal fraction). The obtained correlation between the effective diffusion factor and hyphal fraction shows a large deviation from the correlations reported in the literature so far, giving new and more accurate insights. This knowledge can be used for morphological optimization of filamentous pellets to increase the yield of biotechnological processes.

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“…Lattice Boltzmann method (LBM) is an efficient numerical method for solving the partial differential equations especially with complicated boundary condition such as porous media and particle suspensions. [38][39][40][41][42][43][44] Different from the traditional computational fluid dynamics (CFD), where the macroscopic governing equations (such as Navier-Stokes equations) are solved directly, LBM solves Boltzmann equation in the finite discrete velocities space, while according to the Chapman-Enskog expansion the Navier-Stokes equations can be recovered. 45 Thus, the basic variables in LBM is the particle distribution function, f i .…”

Section: Lattice Boltzmann Methods (Lbm)mentioning

confidence: 99%

An improved immersed moving boundary for hydrodynamic force calculation in lattice Boltzmann method

Chen

Wang

2020

Numerical Meth Engineering

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Summary Particles suspension is considerably prevalent in petroleum industry and chemical engineering. The efficient and accurate simulation of such a process is always a challenge for both the traditional computational fluid dynamics and lattice Boltzmann method. Immersed moving boundary (IMB) method is promising to resolve this issue by introducing a particle‐fluid interaction term in the standard lattice Boltzmann equation, which allows for the smooth hydrodynamic force calculation even for a large grid size relative to the solid particle. Although the IMB method was proved good for stationary particles, the deviation of hydrodynamic force on moving particles exists. In this work, we reveal the physical origin of this problem first and figure out that the internal fluid effect on the hydrodynamic force calculation is not counted in the previous IMB. An improved immersed moving boundary method is therefore proposed by considering the internal fluid correction, which is easy to implement with the little extra computation cost. A 2D single elliptical particle and a 3D sphere sedimentation in Newtonian fluid is simulated directly for the validation of the corrected model by excellent agreements with the standard data.

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Effective gas diffusion coefficient in fibrous materials by mesoscopic modeling

Cited by 34 publications

References 42 publications

Universal law for diffusive mass transport through mycelial networks

Universal law for diffusive mass transport through mycelial networks

From three‐dimensional morphology to effective diffusivity in filamentous fungal pellets

An improved immersed moving boundary for hydrodynamic force calculation in lattice Boltzmann method

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