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This paper deals with the results of an experimental and numerical campaign aimed at characterizing the mechanical response of masonry components and panels made of limestone units kept together by weak air lime mortar joints. The selected air lime mortar, typical of ancient masonry buildings but difficult to be built-up artificially, was specifically prepared for the experimental analyses, with the aim of obtaining a laboratory compression strength of 0.25–0.50 MPa. In the first part of the paper, the performed tests concerning the strength of the units (mean compression strength of 80 MPa) and of the mortar (mean compression strength after 28 days of 0.30 MPa), are described for different curing periods. Moreover, tests of masonry triplets in shear (shear strength of 0.11 MPa for null axial forces) are shown and used in order to establish the main parameters of the Mohr–Coulomb failure criterium. Then, the calibration of a continuous numerical micro-model implemented in Kratos Multiphysics is presented. The model is used for reproducing the behavior of an unreinforced panel in shear made of the studied masonry and to appraise the effectiveness of a FRCM- (Fiber Reinforced Cementitious Matrix) based reinforcement intervention applied. The obtained results proved that FRCM allows to increase the strength of the considered masonry type by about eight times and the ductility by about thirteen times.

We investigate both drainage and spontaneous imbibition processes at the pore scale using a combination of micro- fluidic experiments and lattice-Boltzmann (LB) flow calculations. First, we have fabricated a range of specifically designed etched micro-models to investigate the role of pore shape and throat width on fluid displacement. These designs include junctions with both equal and unequal channel widths in order to achieve a range of capillary entry pressures. All models were etched into Poly(methyl methacrylate) (PMMA) and chemically treated to create a hydrophobic surface. The displacement process is captured via a high-speed video microscope under ambient conditions. The experimental results were then directly compared with LB simulations. For the drainage experiments, we observe that the fluid displacement in the junction follows the Young-Laplace Law. For the case of spontaneous imbibition, however, the models with unequal channel widths display different displacement behaviour. Our experimental observations are confirmed in detail by Lattice Boltzmann Method (LBM) simulations, lending credibility to our observations. Instead of following Young-Laplace filling rules, we observe that the throat in closest proximity fills up first. This has potentially important consequences for calculation of residual saturation of CO 2 at the core scale, which is determined by spontaneous imbibition of brine following CO 2 injection.

Porous structures in materials play a part in many areas of research and development. A couple of examples of this are extraction of water through aquifers and oil through fracking processes. Current understanding of the small scale fluid-fluid interactions in the structure of these porous materials stops at data of the two dimensional interface between the two fluids. This experiment aimed to create three dimensional, transparent, deformable micro-models which are expected allow us to obtain three dimensional data sets of the capillary pressure–saturation–interfacial area per volume relationship. The micro-models were synthesized using a grain deposition technique. Grains were formed using the polymerization of a 5% (v/v) solutions of Irgacur 1173 initiator in poly (ethylene glycol) diacrylate when the solution is exposed to patterns of ultraviolet light (in the range of 435nm to 485nm). These grains are layered in a pre-made plain channel micro-model to create a complex but transparent porous structure. Initial imaging using laser confocal microscopy shows that these micro-models can be used to study three dimensional interactions between fluids in porous structures. Through the creation of these three dimensional micro-models we now have a better way to experimentally model porous materials found in nature which offers many topological possibilities for applications in rock, biology, oil, water, and even food science research.

In this paper a macro-modelling approach for the seismic assessment of Infilled Frame Structures (IFS) is presented. The interaction between frame and infill is simulated through an original approach in which the frame members are modelled by means of lumped plasticity beam–column elements while the infills are described by plane macro-elements. The reliability of the approach is evaluated by means of nonlinear analyses, performed on infilled masonry reinforced concrete structures, for which experimental results are available in literature. The proposed computational strategy is intended to provide a numerical tool suitable for the design and the vulnerability assessment of IFS.

The aim of this research project was to put more physics into theories of two-phase flow. The significance of including interfacial area as a separate variable in two-phase flow and transport models was investigated. In order to investigate experimentally the significance of the inclusion of interfacial area as a separate variable in two-phase flow studies, an artificial porous medium was designed and constructed. First, an extensive and comprehensive review of micro-models materials and manufacturing processes, visualization setups used, and their applications in two-phase flow studies was performed. Based on this review, the manufacturing material for our micro-model studies was chosen. In addition to this, the lack of an optical setup that can visualize flow in elongated micro-models was discussed. In order to calculate quantities like pressure drops, flow rates, relative permeabilities per phase, so as to better design the experimental setup, a pore network model was made. A flow network based on Delaunay triangulation was used to simulate drainage and imbibition under quasi-static conditions. Calculations for capillary pressure, wetting phase saturation, and interfacial area were used to construct the relevant surfaces, for various configurations of the flow network. Intrinsic permeability of the flow network, as well as relative permeability for both phases, were calculated for drainage. Typical flow rates were also calculated, so as to be later compared to experimental values. A micro-model made of silicon and sealed with a glass plate was then manufactured, and it was used to study oil recovery in natural rocks. A novel, all-glass micro-model was used to compare the experimental results to those obtained by the numerical model, under quasi-static conditions, during drainage. A novel optical setup which would allow the dynamic observation of pore scale flow processes in an elongated micro-model was designed and materialized for this purpose. Next, a PDMS micro-model was manufactured by using soft-lithography, to be used in quasi-static and dynamic two-phase flow experiments. A novel process was employed to make PDMS uniformly and stably hydrophobic, so as to resolve the well-known wettability issues of PDMS. Quasi-static and dynamic experimental data for capillary pressure, wetting phase saturation, and specific interfacial area, during drainage, imbibition, and their scanning curves, were extracted from the acquired images. These data were used to test the validity of the new capillarity equation for two-phase flow, by comparing the surfaces plotted for Pc-S-Awn, and verifying that interfacial area should be used as a separate variable in two-phase flow models. Finally, some experimental observations, like snap-off, local imbibition during drainage and vice versa, co-operational filling, and capillary end-effects, which are assumed in numerical models but not seen in experiments were captured for further studies.

The aim of this research project was to put more physics into theories of two-phase flow. The significance of including interfacial area as a separate variable in two-phase flow and transport models was investigated. In order to investigate experimentally the significance of the inclusion of interfacial area as a separate variable in two-phase flow studies, an artificial porous medium was designed and constructed. First, an extensive and comprehensive review of micro-models materials and manufacturing processes, visualization setups used, and their applications in two-phase flow studies was performed. Based on this review, the manufacturing material for our micro-model studies was chosen. In addition to this, the lack of an optical setup that can visualize flow in elongated micro-models was discussed. In order to calculate quantities like pressure drops, flow rates, relative permeabilities per phase, so as to better design the experimental setup, a pore network model was made. A flow network based on Delaunay triangulation was used to simulate drainage and imbibition under quasi-static conditions. Calculations for capillary pressure, wetting phase saturation, and interfacial area were used to construct the relevant surfaces, for various configurations of the flow network. Intrinsic permeability of the flow network, as well as relative permeability for both phases, were calculated for drainage. Typical flow rates were also calculated, so as to be later compared to experimental values. A micro-model made of silicon and sealed with a glass plate was then manufactured, and it was used to study oil recovery in natural rocks. A novel, all-glass micro-model was used to compare the experimental results to those obtained by the numerical model, under quasi-static conditions, during drainage. A novel optical setup which would allow the dynamic observation of pore scale flow processes in an elongated micro-model was designed and materialized for this purpose. Next, a PDMS micro-model was manufactured by using soft-lithography, to be used in quasi-static and dynamic two-phase flow experiments. A novel process was employed to make PDMS uniformly and stably hydrophobic, so as to resolve the well-known wettability issues of PDMS. Quasi-static and dynamic experimental data for capillary pressure, wetting phase saturation, and specific interfacial area, during drainage, imbibition, and their scanning curves, were extracted from the acquired images. These data were used to test the validity of the new capillarity equation for two-phase flow, by comparing the surfaces plotted for Pc-S-Awn, and verifying that interfacial area should be used as a separate variable in two-phase flow models. Finally, some experimental observations, like snap-off, local imbibition during drainage and vice versa, co-operational filling, and capillary end-effects, which are assumed in numerical models but not seen in experiments were captured for further studies.

International audience; In this paper, we present a network method for computing two-phase flows between two rough surfaces with significant contact areas. Low-capillary number drainage is investigated here since one-phase flows have been previously investigated in other contributions. An invasion percolation algorithm is presented for modeling slow displacement of a wetting fluid by a non wetting one between two rough surfaces. Short-correlated Gaussian process is used to model random rough surfaces.The algorithm is based on a network description of the fracture aperture field. The network is constructed from the identification of critical points (saddles and maxima) of the aperture field. The invasion potential is determined from examining drainage process in a flat mini-channel. A direct comparison between numerical prediction and experimental visualizations on an identical geometry has been performed for one realization of an artificial fracture with a moderate fractional contact area of about 0.3. A good agreement is found between predictions and observations.