Experimental Study: The Effect of Pore Shape, Geometrical Heterogeneity, and Flow Rate on the Repetitive Two-Phase Fluid Transport in Microfluidic Porous Media

Geologic subsurface energy storage, such as porous-media compressed-air energy storage (PM-CAES) and underground hydrogen storage (UHS), involves the multi-phase fluid transport in structurally disordered or heterogeneous porous media (e.g., soils and rocks). Furthermore, such multi-phase fluid transport is likely to repeatedly occur due to successive fluid injections and extractions, thus, resulting in cyclic drainage–imbibition processes. To complement our preceding study, we conducted a follow-up study with microfluidic pore-network devices with a square solid shape (Type II) to further advance our understanding on the effect of the pore shape (aspect ratio, Type I: 5–6 \u3e Type II: ~1), pore-space heterogeneity (coefficient of variation, COV = 0, 0.25, and 0.5), and flow rates (Q = 0.01 and 0.1 mL/min) on the repetitive two-phase fluid flow in general porous media. The influence of pore shape and pore-space heterogeneity were observed to be more prominent when the flow rate was low (e.g., Q = 0.01 mL/min in this study) on the examined outcomes, including the drainage and imbibition patterns, the similarity of those patterns between repeated steps, the sweep efficiency and residual saturation of the nonwetting fluid, and fluid pressure. On the other hand, a higher flow rate (e.g., Q = 0.1 mL/min in this study) appeared to outweigh those factors for the Type II structure, owing to the low aspect ratio (~1). It was also suggested that the flow morphology, sweep efficiency, residual saturation, and required pressure gradient may not severely fluctuate during the repeated drainage—imbibition processes; instead, becoming stabilized after 4–5 cycles, regardless of the aspect ratio, COV, and Q. Implications of the study results for PM-CAES and UHS are discussed as a complementary analysis at the end of this manuscript

The taut string approach to statistical inverse problems: theory and applications

A novel solution approach to a class of nonlinear statistical inverse problems with finitely many observations collected over a compact interval on the real line blurred by Gaussian white noise of arbitrary intensity is presented. Exploiting the nonparametric taut string estimator, we prove the state recovery strategy is convergent to a solution of the unnoisy problem at the rate of $n^{−1/2}$ as the number of observations n grows to infinity. Illustrations of the method\u27s application to real-world examples from hydrology, civil & electrical engineering are given andan empirical study on the robustness of our approach is presented

Controlled open-cell two-dimensional liquid foam generation for micro- and nanoscale patterning of materials

Liquid foam consists of liquid film networks. The films can be thinned to the nanoscale via evaporation and have potential in bottom-up material structuring applications. However, their use has been limited due to their dynamic fluidity, complex topological changes, and physical characteristics of the closed system. Here, we present a simple and versatile microfluidic approach for controlling two-dimensional liquid foam, designing not only evaporative microholes for directed drainage to generate desired film networks without topological changes for the first time, but also microposts to pin the generated films at set positions. Patterning materials in liquid is achievable using the thin films as nanoscale molds, which has additional potential through repeatable patterning on a substrate and combination with a lithographic technique. By enabling direct-writable multi-integrated patterning of various heterogeneous materials in two-dimensional or three-dimensional networked nanostructures, this technique provides novel means of nanofabrication superior to both lithographic and bottom-up state-of-the-art techniques

A Distributed Parallel Simulation Environment for Interoperability and Reusability of Models in Military Applications

Interoperability and reusability of models are main concerns in military simulation. In order to improve the interoperability and reusability of models, the model shall be separated with a particular simulation engine, and the modelling framework of models as well as the architecture of the simulation engine should be standardized. This paper describes the architecture and operational concept of simulation environment which has been developed to enhance interoperability an d reusability of models. We named this environment adaptive distributed parallel Simulation environment for Interoperable and reusable models (AddSIM). We suggested a modelling framework to promote model development, portability and interoperability with other models. Also, we proposed a layered architecture to modularise critical capabilities including kernel layer, tool/application layer, support/service layer and external interface. This means that models can be developed independently of a simulation engine and interfaced with it using API. To validate the application feasibility of AddSIM, we set up an anti-air missile engagement situation and performed simulation. In military simulation, it is expected that reusability and interoperability of models will be enhanced by using proposed AddSIM.Defence Science Journal, 2012, 62(6), pp.412-419, DOI:http://dx.doi.org/10.14429/dsj.62.147