Current Understanding of Water Properties inside Carbon Nanotubes

Confined water inside carbon nanotubes (CNTs) has attracted a lot of attention in recent years, amassing as a result a very large number of dedicated studies, both theoretical and experimental. This exceptional scientific interest can be understood in terms of the exotic properties of nanoconfined water, as well as the vast array of possible applications of CNTs in a wide range of fields stretching from geology to medicine and biology. This review presents an overreaching narrative of the properties of water in CNTs, based mostly on results from systematic nuclear magnetic resonance (NMR) and molecular dynamics (MD) studies, which together allow the untangling and explanation of many seemingly contradictory results present in the literature. Further, we identify still-debatable issues and open problems, as well as avenues for future studies, both theoretical and experimental.

A COMPARISON OF EXPERIMENTAL AND NUMERICAL BEHAVIOUR CHARACTERISTICS OF A SHIP ENTERING A LOCK USING BENCHMARK TEST DATA

This paper discusses several papers that were presented at the 3rd International Conference on Ship Manoeuvring in Shallow and Confined Water, which had a non-exclusive focus on Ship Behaviour in Locks. For this conference, experimental model test data obtained at Flanders Hydraulics Research had been made public and researchers were encouraged to compare numerical with experimental results [1]. Data of benchmark tests carried out both with self- propelled and captive models were used by researchers for comparison with various numerical tools. The objective of this paper is to give a selected overview of how accurately numerical tools are presently able to predict the hydrodynamic forces that occur on ships approaching locks. Based on this, the paper concludes that experiments and numerical tools complement each other.

VERTICAL AND SLOPED BANK EFFECTS ON DIFFERENT SHIP TYPES

The Author describes how the bank effects that occur when a ship sails in confined waters can be studied with a numerical method. Being involved in the Knowledge Centre “Manoeuvring in Shallow & Confined Water” (Ghent University & Flanders Hydraulics Research, Antwerp, Belgium), we have read the paper with interest.

INSIGHTS INTO THE FLOW WITHIN THE WELL DOCK OF A MOTHERSHIP DURING FEEDER VESSEL DOCKING MANOEUVRES

An experimental campaign has been undertaken to explore the flow around a feeder vessel as it manoeuvres in and out of the well dock of a mothership. The parent hulls for this study are drawn from the floating harbour transhipper concept created by Sea Transport Corporation. Laser measurement techniques have been employed to analyse the flow field within the well dock while the feeder vessel both enters and departs. For the Master of the feeder vessel to safely perform these manoeuvres, the complex flows resulting from the highly confined nature of the well dock concept need to be understood and potentially mitigated. It is shown that the inclusion of vents in the well dock can significantly influence the flow and that their effectiveness is determined by the size of the vents. This study further progresses the authors’ recent work on the same novel concept where the confined water effect of the well dock and inclusion of vents is quantified for both the seakeeping behaviour and the docking/departure performance. It is concluded that the use of vents is very beneficial when a feeder vessel docks or departs the well dock, however a compromise on the vent size must be reached in order to reduce adverse effects on feeder vessel motions when docked and exposed to a seaway. It is likely that the optimum solution, that covers all operational parameters, only requires the inclusion of relatively small vents.

CFD STUDY OF SHIP-TO-BANK INTERACTION

Ship-to-bank interaction is a complex physical phenomenon that involves not only in the asymmetric pressure field near banks or channels but also shallow water effect. Traditionally many experimental studies were carried out in this field. As numerical method is getting popular, there were various computational approaches as well. In this study, flow around a container ship in confined water is investigated with the open source CFD (Computational Fluid Dynamics) toolbox, OpenFOAM. Computations with several bank arrangements and different settings are performed. The OpenFOAM results are also compared to experiment results for validation.

Atomistic molecular dynamics insights on water local structure and dynamics on different surfaces of zeolitic-imidazolate frameworks

Most of chemistry in nanoporous materials with small pore sizes and windows is known to occur on the surface which is in immediate contact with substrate/solvent, rather than inside pores and channels. Here, we report the results of our comprehensive atomistic molecular dynamics simulations on deciphering the intermolecular hydrogen bond network of water on outer surface of a nanoparticle model of ZIF-8 vs. inner surfaces of its pristine crystalline bulk model. Using a finite ~5.1 nm nanoparticle model with edges containing under--coordinated Zn2+ metal sites we show that water exposed to the surface of the nanoparticle exhibits both interfacial and bulk-like characters. Furthermore, we illustrate that as water content increases larger droplets are formed with water molecules starting to diffuse into the nanopores. While the confined water in the crystalline bulk simulations is pushed to the vacant pores due to hydrophobic inner surfaces, the outer surface water molecules form chemical bonds with under--coordinated Zn2+ metal sites which act as nucleation sites for the water droplets to form and hence making the surface hydrophilic. By adapting a similar mechanism to the dangling linker defect formation mechanism, we probe the tendency of the outer surface of ZIF-8 nanoparticles to water attack and hydrolysis. Results presented in this work are useful in designing more robust materials for applications in humid environments.

Control of Water Inrush from Longwall Floor Aquifers Using a Division Paste Backfilling Method

Aiming at the problem of the safety mining problems of longwall paste filling working face under buildings on high confined water in the Daizhuang Coal Mine, the paste filling mining method was used. A series of theoretical analyses, numerical simulations, and field measurements were applied. The results showed that when the filling interval of the working face increases from 1.2 m to 3.6 m, no significant change is found in the depth of the perforated plastic zone of the floor strata. According to the types of water-conducting cracks in the floor strata of the working face 11607, the floor strata are divided into the floor intact area, the structure developed area, and the floor weak area. Based on that, the measures for preventing and controlling the floor failure in the paste filling working face are proposed. Furthermore, the failure depth of the floor of the test working face was detected by the on-site water injection method, and the results showed that the maximum failure depth of the floor of the test working face was about 3 m.