Explicit numerical simulation of non-creeping single phase flow in porous media

Porous media and transport within them play important roles across industries and beyond, including in water and pollutant transport in soils, flow in petroleum and geothermal reservoirs, and water treatment in deep bed filtration to list just a few key examples. The study of such flows has traditionally been dominated by experiment. Simulation is, however, playing an increasing role in this field both because of the advent of X-ray microtomography (XRMT), which now permits the mapping of pore structures down to sub-micrometer resolution, and the ubiquitous availability of powerful compute clusters built on cheap commodity machines. Simulation in this context involves solving for the flow field in a model of a porous solid derived from XRMT - in this sense, the simulations mimic reality and are hence termed by us as explicit numerical simulation (ENS). The particular challenge in doing ENS is correctly solving the flow problem in extremely complex geometries. This challenge has led to the use of various methods such as lattice-gas automata (LGA) and the related lattice-Boltzmann method (LBM), which are particularly suited to resolving flows in complex geometries. All of this work to date has been restricted to low velocity flows termed Darcy flows because of limitations associated with LGA, LBM and other methods. There is, however, a range of applications where higher speed flows are of relevance and hence extension of the ENS approach to higher speed flows in porous media is important. This has been done here using an LGA model that does not include the deficiency of more standard LGA models that restricts them to slow flows. The thesis first details this little-known and used LGA model before demonstrating it on a range of benchmark problems. The model is then used to predict ab initio the hydrodynamic properties of a random packing from the Darcy to the turbulent regime. Comparison with experiment is excellent. The approach is then used to study, for the first time to our knowledge, the interstitial flow patterns from the Darcy to turbulent regimes

Nanoparticle transport in saturated porous medium using magnetic resonance imaging

Transport study of nanoparticle (NP) through matrix flow dominated aquifer sand and soils have significant influence in natural systems. To quantify the transport behaviour, magnetic resonance imaging (MRI) was used to image the iron oxide based nanoparticle, Molday ION (carboxyl terminated) through saturated sandstone rock core. T2-weighted images were acquired and the changes in image intensity were calibrated to get a quantitative concentration profiles at various time intervals. These profiles were evaluated through CXTFIT transport model to estimate the transport parameters. These parameters are estimated at various points along the length of the column while classical breakthrough curve analysis cannot provide these details. NP–surface interactions were investigated using DLVO (Derjaguin–Landau–Verwey–Overbeek) theory. The dispersion coefficients (2.55–1.21 × 10−7 m2/s) were found to be decrease with distance, deposition rate constant k (6.70–9.13 × 10−4 (1/s)) and fast deposition rate constant kfast (4.32–8.79 × 10−2 (1/s)) were found to be increase with distance. These parameter variations over length will have a scaling up impact in developing transport models for environmental remediation and risk assessment schemes

The emerging use of magnetic resonance imaging to study river bed dynamics

The characterization of surface and sub-surface sedimentology has long been of interest to gravel-bed river researchers. The determination of surface structure is important as it exerts control over bed roughness, near-bed hydraulics and particle entrainment for transport1. Similarly, interpretation of the sub-surface structure and flow is critical in the analysis of bed permeability, the fate of pollutants and maintaining healthy hyporheic ecology 2.For example, many invertebrates (e.g. mayfly, caddis) and fish (e.g. salmon) lay their eggs below the river bed surface, and rely on sub-surface flows to supply the necessary oxygen and nutrients. Whilst turbulent surface flows drive these small sub-surface flows, they can also convey sand and silts that clogs the surface and sub-surface pore spaces. Reduction in sub-surface flows can starve eggs of oxygen such that larvae or juveniles do not emerge. This is particularly critical in Scottish gravel-bed rivers as the rising supply and deposition of fine sediment (silts and sands) is contributing to the dramatic decline in wild salmon. In order to gain a better understanding of such flow-sediment-ecology interactions in river systems, laboratory experiments are conducted using long rectangular flow tanks called “flumes”, see figure 1a,1b. Here, traditional techniques for analysing sediment structure are typically constrained to 1D or 2D approaches, such as coring, photography etc. Even where more advanced techniques are available (e.g. laser displacement scanning), these tend to be restricted to imaging the surface of the sediment bed. Using Magnetic Resonance Imaging (MRI) overcomes these limitations, providing researchers with a non-invasive technique with which to provide novel 3D spatio-temporal data on the internal pore structure. In addition the important sub-surface flows can be investigated by adding MRI contrast agents to the flowing surface water

Characterization of flow transport within pore spaces of an open-work gravel bed

Analysis of the flow dynamics within the near-bed and sub-surface regions of river bed sediment is critical in understanding fluid exchange and related chemical transfer/reactions. The knowledge in above is limited as these regions are difficult to measure using traditional instrumentation methods. In this paper, we tried the use of Magnetic Resonance Imaging (MRI) technique to non-invasively image flow dynamics of simulated river bed. We developed a bespoke MRI-compatible open-channel flume in order to acquire real-time flow images from within the MRI bore and used contrast agent (Gd-DTPA) as a tracer through an immobile, porous gravel bed. Single MR Image slices along the flume length were obtained for analysis. The flow tracer images from within the sediment bed are calibrated from the output data in order to provide fully quantitative maps of tracer concentration at regular time intervals. These ‘white-box’ (i.e. data from within the porous bed) tracer profiles were evaluated with the CXTFIT computer package to estimate the transport parameters. The intention was both, to illustrate the appropriateness of MRI for flow-sediment research and to analyse the relationship between tracer dispersion and gravel framework structure

The emerging use of magnetic resonance imaging to study river bed dynamics

The characterization of surface and sub-surface sedimentology has long been of interest to gravel-bed river researchers. The determination of surface structure is important as it exerts control over bed roughness, near-bed hydraulics and particle entrainment for transport1. Similarly, interpretation of the sub-surface structure and flow is critical in the analysis of bed permeability, the fate of pollutants and maintaining healthy hyporheic ecology 2.For example, many invertebrates (e.g. mayfly, caddis) and fish (e.g. salmon) lay their eggs below the river bed surface, and rely on sub-surface flows to supply the necessary oxygen and nutrients. Whilst turbulent surface flows drive these small sub-surface flows, they can also convey sand and silts that clogs the surface and sub-surface pore spaces. Reduction in sub-surface flows can starve eggs of oxygen such that larvae or juveniles do not emerge. This is particularly critical in Scottish gravel-bed rivers as the rising supply and deposition of fine sediment (silts and sands) is contributing to the dramatic decline in wild salmon. In order to gain a better understanding of such flow-sediment-ecology interactions in river systems, laboratory experiments are conducted using long rectangular flow tanks called “flumes”, see figure 1a,1b. Here, traditional techniques for analysing sediment structure are typically constrained to 1D or 2D approaches, such as coring, photography etc. Even where more advanced techniques are available (e.g. laser displacement scanning), these tend to be restricted to imaging the surface of the sediment bed. Using Magnetic Resonance Imaging (MRI) overcomes these limitations, providing researchers with a non-invasive technique with which to provide novel 3D spatio-temporal data on the internal pore structure. In addition the important sub-surface flows can be investigated by adding MRI contrast agents to the flowing surface water

IN-SITU KINETIC STUDIES OF THE HOMOGENEOUS CATALYTIC HYDROFORMYLATION WITH UNMODIFIED COBALT CARBONYLS

Master'sMASTER OF ENGINEERIN

The emerging use of magnetic resonance imaging to study river bed dynamics

The characterization of surface and sub-surface sedimentology has long been of interest to gravel-bed river researchers. The determination of surface structure is important as it exerts control over bed roughness, near-bed hydraulics and particle entrainment for transport1. Similarly, interpretation of the sub-surface structure and flow is critical in the analysis of bed permeability, the fate of pollutants and maintaining healthy hyporheic ecology 2.For example, many invertebrates (e.g. mayfly, caddis) and fish (e.g. salmon) lay their eggs below the river bed surface, and rely on sub-surface flows to supply the necessary oxygen and nutrients. Whilst turbulent surface flows drive these small sub-surface flows, they can also convey sand and silts that clogs the surface and sub-surface pore spaces. Reduction in sub-surface flows can starve eggs of oxygen such that larvae or juveniles do not emerge. This is particularly critical in Scottish gravel-bed rivers as the rising supply and deposition of fine sediment (silts and sands) is contributing to the dramatic decline in wild salmon. In order to gain a better understanding of such flow-sediment-ecology interactions in river systems, laboratory experiments are conducted using long rectangular flow tanks called “flumes”, see figure 1a,1b. Here, traditional techniques for analysing sediment structure are typically constrained to 1D or 2D approaches, such as coring, photography etc. Even where more advanced techniques are available (e.g. laser displacement scanning), these tend to be restricted to imaging the surface of the sediment bed. Using Magnetic Resonance Imaging (MRI) overcomes these limitations, providing researchers with a non-invasive technique with which to provide novel 3D spatio-temporal data on the internal pore structure. In addition the important sub-surface flows can be investigated by adding MRI contrast agents to the flowing surface water

Colorimetric sensors for rapid detection of various analytes

Sensor technology for the rapid detection of the analytes with high sensitivity and selectivity has several challenges. Despite the challenges, colorimetric sensors have been widely accepted for its high sensitive and selective response towards various analytes. In this review, colorimetric sensors for the detection of biomolecules like protein, DNA, pathogen and chemical compounds like heavy metal ions, toxic gases and organic compounds have been elaborately discussed. The visible sensing mechanism based on Surface Plasmon Resonance (SPR) using metal nanoparticles like Au, Ag, thin film interference using SiO2 and colorimetric array-based technique have been highlighted. The optical property of metal nanoparticles enables a visual color change during its interaction with the analytes owing to the dispersion and aggregation of nanoparticles. Recently, colorimetric changes using silica substrate for detection of protein and small molecules by thin film interference as a visible sensing mechanism has been developed without the usage of fluorescent or radioisotopes labels. Multilayer of biomaterials were used as a platform where reflection and interference of scattering light occur due to which color change happens leading to rapid sensing. Colorimetric array-based technique for the detection of organic compounds using chemoresponsive dyes has also been focused wherein the interaction of the analytes with the substrate coated with chemoresponsive dyes gives colorimetric change. (C) 2017 Elsevier B.V. All rights reserved

Design and Fabrication of Biosensor for a Specific Microbe by Silicon-Based Interference Color System

Peer reviewed: TrueAcknowledgements: Takatoshi Kinoshita would like to Thanks to Kenji Yamaguchi and Mineo Sugiyama, Pokka Corporation, Shikatsu-cho, Nishikasugai-gun, Aichi-4818515, Japan for their continued support.Publication status: PublishedIn this paper, one of the great challenges faced by silicon-based biosensors is resolved using a biomaterial multilayer. Tiny biomolecules are deposited on silicon substrates, producing devices that have the ability to act as iridescent color sensors. The color is formed by a coating of uniform microstructures through the interference of light. The system exploits a flat, RNA-aptamer-coated silicon-based surface to which captured microbes are covalently attached. Silicon surfaces are encompassed with the layer-by-layer deposition of biomolecules, as characterized by atomic force microscopy and X-ray photoelectron spectroscopy. Furthermore, the results demonstrate an application of an RNA aptamer chip for sensing a specific bacterium. Interestingly, the detection limit for the microbe was observed to be 2 × 106 CFUmL−1 by visually observed color changes, which were confirmed further using UV-Vis reflectance spectrophotometry. In this report, a flexible method has been developed for the detection of the pathogen Sphingobium yanoikuyae, which is found in non-beverage alcohols. The optimized system is capable of detecting the specific target microbe. The simple concept of these iridescent color changes is mainly derived from the increase in thickness of the nano-ordered layers.</jats:p