Comparison of advanced discretization techniques for image-based modelling of heterogeneous porous rocks

Abstract

This contribution presents an assessment of computational techniques enabling automated simulations of complex porous rocks microstructures based on 3D imaging techniques. A subset of a CT-scanned sandstone sample is used to compare the results obtained by two advanced discretization frameworks. Raw scan results are processed by a level set-based segmentation technique to produce smooth geometries prone to finite element discretizations. A recently developed technique is outlined for conforming mesh generation for complex porous geometries described implicitly by functions. This allows generating high quality tetrahedral meshes with selective refinement. Next to this, a technique that uses a kinematic enrichment by incompatible modes to represent the heterogeneous geometry is explained. Both techniques use the same implicit geometry as main input for the simulations. Mechanical simulations are conducted on a subset of a scanned sample of a sandstone under triaxial loading conditions for isotropic compressive loading and for loading conditions involving a stress deviator. The results are compared and discussed based on local stress distributions and on a Mohr-Coulomb criterion with tensile cut-off. The results show that both discretization strategies yield complementary tools and allow envisioning automated simulations based on raw CT scan data for porous rocks exhibiting complex pore space morphologies.

Efficient computational modelling of closed cell metallic foams using a morphologically controlled shell geometry

“…It would be useful in a future work to extend the developed methodology to directly incorporate explicit experimental geometrical information into the computational modelling of closed cell foams. As a complement to the computational tools developed so far, 3D/shell finite element models can be built using the cell structures obtained directly from CT imaging techniques in order to capture the actual microscale geometry, see [54]. This is planned for 38 closed cell metallic foams as future work.…”