Tomography-based determination of permeability and Dupuit-Forchheimer coefficient of characteristic snow samples

A tomography-based methodology for the mass transport characterization of snow is presented. Five samples, characteristic for a wide range of seasonal snow, are considered. Their three-dimensional (3-D) geometrical representations are obtained by micro-computed tomography and used in direct pore-level simulations to numerically solve the governing mass and momentum conservation equations, allowing for the determination of their effective permeability and Dupuit-Forchheimer coefficient. The extension to the Dupuit-Forchheimer coefficient is useful near the snow surface, where Reynolds numbers higher than unity can appear. Simplified semi-empirical models of porous media are also examined. The methodology presented allows for the determination of snow's effective mass transport properties, which are strongly dependent on the snow microstructure and morphology. These effective properties can, in turn, readily be used in snowpack volume-averaged (continuum) models such as strongly layered samples with macroscopically anisotropic properties

Micro-Computed Tomography Based Computational Fluid Dynamics for the Determination of Shear Stresses in Scaffolds Within a Perfusion Bioreactor

Perfusion bioreactors are known to exert shear stresses on cultured cells, leading to cell differentiation and enhanced extracellular matrix deposition on scaffolds. The influence of the scaffold's porous microstructure is investigated for a polycaprolactone (PCL) scaffold with a regular microarchitecture and a silk fibroin (SF) scaffold with an irregular network of interconnected pores. Their complex 3D geometries are imaged by micro-computed tomography and used in direct pore-level simulations of the entire scaffold-bioreactor system to numerically solve the governing mass and momentum conservation equations for fluid flow through porous media. The velocity field and wall shear stress distribution are determined for both scaffolds. The PCL scaffold exhibited an asymmetric distribution with peak and plateau, while the SF scaffold exhibited a homogenous distribution and conditioned the flow more efficiently than the PCL scaffold. The methodology guides the design and optimization of the scaffold geometry

Micro-Computed Tomography Based Computational Fluid Dynamics for the Determination of Shear Stresses in Scaffolds Within a Perfusion Bioreactor

Perfusion bioreactors are known to exert shear stresses on cultured cells, leading to cell differentiation and enhanced extracellular matrix deposition on scaffolds. The influence of the scaffold’s porous microstructure is investigated for a polycaprolactone (PCL) scaffold with a regular microarchitecture and a silk fibroin (SF) scaffold with an irregular network of interconnected pores. Their complex 3D geometries are imaged by micro-computed tomography and used in direct pore-level simulations of the entire scaffold–bioreactor system to numerically solve the governing mass and momentum conservation equations for fluid flow through porous media. The velocity field and wall shear stress distribution are determined for both scaffolds. The PCL scaffold exhibited an asymmetric distribution with peak and plateau, while the SF scaffold exhibited a homogenous distribution and conditioned the flow more efficiently than the PCL scaffold. The methodology guides the design and optimization of the scaffold geometry.ISSN:1573-9686ISSN:0191-5649ISSN:0090-696

Micro-Computed Tomography Based Computational Fluid Dynamics for the Determination of Shear Stresses in Scaffolds Within a Perfusion Bioreactor

Perfusion bioreactors are known to exert shear stresses on cultured cells, leading to cell differentiation and enhanced extracellular matrix deposition on scaffolds. The influence of the scaffold's porous microstructure is investigated for a polycaprolactone (PCL) scaffold with a regular microarchitecture and a silk fibroin (SF) scaffold with an irregular network of interconnected pores. Their complex 3D geometries are imaged by micro-computed tomography and used in direct pore-level simulations of the entire scaffold-bioreactor system to numerically solve the governing mass and momentum conservation equations for fluid flow through porous media. The velocity field and wall shear stress distribution are determined for both scaffolds. The PCL scaffold exhibited an asymmetric distribution with peak and plateau, while the SF scaffold exhibited a homogenous distribution and conditioned the flow more efficiently than the PCL scaffold. The methodology guides the design and optimization of the scaffold geometry