Lattice Boltzmann simulations of diffusion through native and steam-exploded softwood bordered pits

Kvist, Patric; Therning, Adam; Gebäck, Tobias; Rasmuson, Anders

doi:10.1007/s00226-017-0938-1

Cited by 5 publications

(11 citation statements)

References 32 publications

(30 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other than the inherent polymers found in wood, enzymes are of interest in the biorefinery concept to aid in the hydrolysis of polysaccharides (Hasunuma et al 2013). Diffusion of polysaccharides and enzymes are hindered by the wood microstructure (Wu et al 2009;Kvist et al 2017), and to increase the overall mass transport rate, a pretreatment step is often used.…”

Section: Introductionmentioning

confidence: 99%

Using fluorescent probes and FRAP to investigate macromolecule diffusion in steam-exploded wood

et al. 2018

Self Cite

View full text Add to dashboard Cite

Diffusion of fluorescently labeled dextran of varying molecular weight in wood pretreated by steam explosion was studied with a confocal microscope. The steam explosion experiments were conducted at relatively mild conditions relevant for materials biorefinery at a pressure of 14 bars for 10 min. The method of fluorescence recovery after photobleaching (FRAP) was used to perform diffusion measurements locally in the wood microstructure. It was found that the FRAP methodology can be used to observe differences in the diffusion coefficient based on localization in the microstructure, i.e., earlywood, latewood, and cell wall. Microscopic changes due to steam explosion were seen to increase diffusion of the smaller 3-kDa dextran diffusion probe in the earlywood, while the latewood structure was not affected in any significant way. Macroscopic changes to the structure in the form of ruptures due to the steam explosion pretreatment were observed to increase the rate of diffusion for the larger 40-kDa dextran probe.

show abstract

Section: Introductionmentioning

confidence: 99%

Using fluorescent probes and FRAP to investigate macromolecule diffusion in steam-exploded wood

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…To compare the size of the pits, an equivalent diameter of a sphere with the same volume as each pit was calculated. The volume for each pit was compared with an average value based on published data (Petty 1972;Siau 1984;Hacke et al 2004;Trtik et al 2007;Schulte 2012;Schulte et al 2015), similar to what was done in a previous study by the authors (Kvist et al 2017). The volume of the pit was calculated by assuming a spheroid shape with an average margo diameter of 16.10 μm and a length from aperture to aperture of 5.27 μm.…”

Section: Wood Microstructurementioning

confidence: 97%

“…A variable diffusion coefficient was used in the simulation to differentiate the bordered pits from the rest of the open space in the lumina. The diffusion coefficient inside the space of the pits was based on a previous study by the authors (Kvist et al 2017), where the effect of steam explosion on a bordered pit was investigated. Figure 1 shows a cross section and a volume of the images from the tomography data.…”

Section: Modelingmentioning

confidence: 99%

“…It would not be computationally feasible to solve the diffusion equation with such a large difference in length scale. In the present work, two different length scales were utilized by using previous simulation results by the authors (Kvist et al 2017) of diffusion through one bordered pit, as input for the local diffusion coefficient of the pits. The pits were found in the 3D structure generated by X-ray tomography images using a watershed segmentation algorithm (Meyer 1994).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A multi-scale model for diffusion of large molecules in steam-exploded wood

2020

Self Cite

View full text Add to dashboard Cite

In this paper, multi-scale modeling was used to resolve diffusion in steam-exploded wood at tracheid scales including sub-micrometer features of bordered pits. Simulations were performed using the lattice Boltzmann method with high-resolution X-ray tomography image data as the input for the microstructure. The results show an effective method for utilizing a variable diffusion coefficient to implement two length scales. This circumvents the need to resolve the bordered pits in detail, which requires massive computing power. Instead, the effective diffusion coefficient for one bordered pit is used as input for this model. Results based on the present model are comparable to experimental data. This methodology can be extended to more structural features at the microscale of wood, such as latewood and the cell wall. Obtaining a map of different diffusion coefficients based on features and scale gives a better overall understanding of diffusion and the importance of mass transport with regard to the pretreatment of wood.

show abstract

“…The thread-like margo and the torus inside the chamber of the pit could not be resolved, which is not surprising since they are both below 0.5 µm in thickness. A general average value for earlywood pits in softwoods is a pit opening diameter (the aperture) of 3.7 µm with an inner diameter (the outer diameter of the margo) of 16.1 µm (Kvist et al 2017). The size would indicate that the X-ray tomography has difficulties to resolve the small chamber depth, approximately 2 µm, of the pit.…”

Section: Region Of Interest and Sub-volumesmentioning

confidence: 99%

Lattice Boltzmann simulations of diffusion in steam-exploded wood

et al. 2019

Self Cite

View full text Add to dashboard Cite

Diffusion of large molecules throughout the porous microstructure of wood pretreated with steam explosion was investigated by using the lattice Boltzmann method for simulations. Wood samples were investigated with high-resolution X-ray tomography to effectively reconstruct an accurate geometry of the structural changes that ensue after pretreatment. Samples of approximately 1 mm 3 with voxel sizes from 0.5 to 1 μm were examined with X-ray imaging. These large volumes, relative to what reasonably can be simulated, were divided into sub-volumes and were further reconstructed into geometries suited for the LBM simulations. The transient development of the concentration was investigated, and the effective diffusion coefficient at steady state was computed. Diffusion rates were found to increase significantly in the transversal direction due to the steam explosion pretreatment. The increase was observed both in the time needed for solutes to diffuse throughout the pores and in the effective diffusion coefficient. A shorter diffusion pathway and a higher connectivity between pores were found for the pretreated samples, even though the porosity was similar and the pore size distribution narrower than the native sample. These results show that local mass transport depends not only on porosity but also, in a complex manner, on pore structure. Thus, a more detailed analysis of pore space structure using tomography data, in combination with simulations, enables a more general understanding of the diffusional process.

show abstract

Lattice Boltzmann simulations of diffusion through native and steam-exploded softwood bordered pits

Cited by 5 publications

References 32 publications

Using fluorescent probes and FRAP to investigate macromolecule diffusion in steam-exploded wood

Using fluorescent probes and FRAP to investigate macromolecule diffusion in steam-exploded wood

A multi-scale model for diffusion of large molecules in steam-exploded wood

Lattice Boltzmann simulations of diffusion in steam-exploded wood

Contact Info

Product

Resources

About