A finite element heterogeneous multiscale method is proposed for solving the Stokes problem in porous media. The method is based on the coupling of an effective Darcy equation on a macroscopic mesh, with unknown permeabilities recovered from micro finite element calculations for Stokes problems on sampling domains centered at quadrature points in each macro element. The numerical method account...

We present a multiscale micro-macro method for the Stokes problem in heterogeneous media. The macroscopic method discretizes a Darcy problem on a coarse mesh with permeability data recovered from solutions of Stokes problems around quadrature points. The accuracy of both the macro and the micro solvers is controlled by appropriately coupled a posteriori error indicators, while the total cost of...

In the present investigation, γ-alumina nanoparticles with particle sizes less than 10 nm, high specific surface area (351 m2/g), high pore volumes and relatively narrow pore sizes distribution was prepared via sol-gel method in presence of aluminum isopropoxide as an aluminum precursor, distilled water, acetic acid as hydrolysis rate controller and tert-butanol as solvent. They had meso ...

Thuja plicata is a coniferous tree which displays remarkable water channelling properties. In this article, an easily fabricated mesh inspired by the hierarchical macro surface structure of Thuja plicata branchlets is described which emulates this efficient water collection behaviour. The key parameters are shown to be the pore size, pore angle, mesh rotation, tilt angle (branch droop) and laye...

Low field NMR T2 distribution is an efficient tool for characterizing pore size distribution in porous media. For multimodal systems, a new technique called T2-storeT2 allows the analysis of diffusional pore to pore exchange that is extremely useful for the characterization of connectivity. This technique uses 2D inverse Laplace techniques and produces T2-T2 maps. Qualitatively, a system is cou...

Bimodal macro-mesoporous silica networks have been prepared in a simple one-pot synthesis using an inexpensive non-toxic surfactant and tetraethoxysilane as a silica precursor. These novel materials show high pore volumes with interparticle macropores and templated mesopores (average pore size 3.0 nm) in 20 nm thick walls. The key properties of these materials can be tailored by controlling the...

A new rapid, very simple and one-step sol-gel strategy for the large-scale preparation of highly porous γ-Al₂O₃ is presented. The resulting mesoporous alumina materials feature high surface areas (400 m² g-1), large pore volumes (0.8 mL g-1) and the γ-Al₂O₃ phase is obtained at low temperature (500 °C). The main advantages and drawbacks of different preparations of mesoporous alumina materials ...

A simple porous gel synthesis method is proposed in this paper. We found that the sequential modification of conventional radical polymerization gives rise to pore formation in acrylamide gels and investigated the parameters that are responsible for controlling the number and the size of pores. Pore formation is dominated by the amount of polymerization initiator (ammonium persulfate), accelera...