The effect of surface tension on free surface flow induced by a point sink in a fluid of finite depth

Solutions are presented to the problem of steady, axisymmetric flow of an inviscid fluid into a point sink. The fluid is of finite depth and has a free surface. Two numerical schemes, a spectral method and an integral equation approach, are implemented to confirm results for the maximum-flow-rate steady solution for each configuration. The effects of surface tension and sink depth are included and constitute the new component of the work. Surface tension has the effect of increasing the maximum flow rate at which steady-state solutions can exist

Towards hydrogen energy: progress on catalysts for water splitting

This article reviews some of the recent work by fellows and associates of the Australian Research Council Centre of Excellence for Electromaterials Science (ACES) at Monash University and the University of Wollongong, as well as their collaborators, in the field of water oxidation and reduction catalysts. This work is focussed on the production of hydrogen for a hydrogen-based energy technology. Topics include: (1) the role and apparent relevance of the cubane-like structure of the Photosystem II Water Oxidation Complex (PSII-WOC) in non-biological homogeneous and heterogeneous water oxidation catalysts, (2) light-activated conducting polymer catalysts for both water oxidation and reduction, and (3) porphyrin-based light harvesters and catalysts

Genetic Sharing with Cardiovascular Disease Risk Factors and Diabetes Reveals Novel Bone Mineral Density Loci.

Bone Mineral Density (BMD) is a highly heritable trait, but genome-wide association studies have identified few genetic risk factors. Epidemiological studies suggest associations between BMD and several traits and diseases, but the nature of the suggestive comorbidity is still unknown. We used a novel genetic pleiotropy-informed conditional False Discovery Rate (FDR) method to identify single nucleotide polymorphisms (SNPs) associated with BMD by leveraging cardiovascular disease (CVD) associated disorders and metabolic traits. By conditioning on SNPs associated with the CVD-related phenotypes, type 1 diabetes, type 2 diabetes, systolic blood pressure, diastolic blood pressure, high density lipoprotein, low density lipoprotein, triglycerides and waist hip ratio, we identified 65 novel independent BMD loci (26 with femoral neck BMD and 47 with lumbar spine BMD) at conditional FDR < 0.01. Many of the loci were confirmed in genetic expression studies. Genes validated at the mRNA levels were characteristic for the osteoblast/osteocyte lineage, Wnt signaling pathway and bone metabolism. The results provide new insight into genetic mechanisms of variability in BMD, and a better understanding of the genetic underpinnings of clinical comorbidity

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Critical withdrawal from a two-layer fluid / by Graeme C. Hocking

Bibliography: leaves 77-7878 leaves : ill. (some col.) ; 30 cm.Thesis (Ph.D.)--University of Adelaide, Dept. of Applied Mathematics, 198

A note on withdrawal from a two-layer fluid through a line sink in a porous medium

The steady response of the free surface of a fluid in a porous medium is considered during extraction of the fluid through a line sink. A conformal mapping approach is used to derive exact solutions to a family of problems in which the line sink is place at the apex of a wedge-shaped impermeable boundary, including the limiting cases of an ubounded aquifer and a flat-bottomed aquifer of finite depth. Both critical cusp solutions and sub-critical solutions are computed exactly as a Fourier sine series. doi:10.1017/S144618110800028

A note on axisymmetric supercritical coning in a porous medium

The steady response of a fluid with two layers of different density in a porous medium is considered during extraction through a point sink. Supercritical withdrawal in which both layers are being withdrawn is investigated using a spectral method. We show that for each withdrawal rate, there is a single entry angle of the interface into the point sink. As the flow rate decreases the angle of entry steepens until it becomes almost vertical, at which point the method fails. This limit is shown to correspond to the upper bound on sub-critical (single-layer) flow. doi:10.1017/S144618111400017

A rational approximation to the evolution of a free surface during fluid withdrawal through a point sink

The time varying flow in which fluid is withdrawn from a reservoir through a point sink of variable strength beneath a free surface is considered. Asymptotic techniques are used to derive an approximate solution to the flow that is valid at intermediate times, giving a simple rational approximation to track changes in the free surface for any temporal variations in the sink strength. Comparisons with numerical simulations are given, showing that the approximation has wide applicability

The lens of freshwater in a tropical island: the two interface case

The lens of freshwater beneath a tropical island is vital for supplying water to the island population. We consider the circumstances under which artificial recharge through a single inlet point will maintain the lens if no natural recharge occurs. A Greens function approach derives an integral equation that is solved numerically for the case in which two interfaces exist---one between salt and freshwater and one between freshwater and air. There appear to be upper and lower bounds on the flow rates that produce steady interface shapes. The height of the seepage faces is dominated by the density ratios. References L. K. Forbes, G. C. Hocking and S. Wotherspoon, 2004, Salt-water up-coning during extraction of fresh water from a tropical island, J. Eng. Math, 48, 2004, 69--91. doi:10.1023/B:ENGI.0000009517.28682.6f G. C. Hocking and L. K. Forbes, The lens of freshwater in a tropical island - 2d withdrawal, Comp. and Fluids, 33, 2004, 19--30. doi:10.1016/S0045-7930(03)00035-5 G. C. Hocking and H. Zhang, A note on withdrawal from a two-layer fluid through a line sink in a porous medium, ANZIAM J., 50, 2008, 101--110. doi:10.1017/S144618110800028X C. D. Langevin, M. T. Stewart and C. M. Beaudoin, Effects of sea water canals on fresh water resources: an example from Big Pine Key, Florida, Ground Water, 36, 1998, 503--513. doi:10.1111/j.1745-6584.1998.tb02822.x S. K. Lucas, J. R. Blake and A. Kucera, A boundary-integral method applied to water coning in oil reservoirs, J. Austral. Math. Soc. Ser. B, 32, 1991, 261--283. doi:10.1017/S0334270000006858 M. Muskat and R. B. Wyckoff, An approximate theory of water coning in oil production, Trans. AIME, 114, 1935, 144--163. P. Y. Polubarinova-Kochina, Unsteady seepage with an interface (in Russian), Moscow: Dokl. Nauk, S. S. S. R., 1949, 173--176 C. Ruppel, G. Schultz and S. Kruse, Anomalous fresh water lens morphology on a strip barrier island, Ground Water, 38, 2000, 872--881. doi:10.1111/j.1745-6584.2000.tb00686.x H. Zhang and G. C. Hocking, Withdrawal of layered fluid through a line sink in a porous medium, J. Austral. Math. Soc. Ser. B, 38, 1996, 240--254. doi:10.1017/S033427000000063

Dispersal of hydrogen in the retina – a three-layer model

Two simple mathematical models of advection and diffusion of hydrogen within the retina are discussed. The work is motivated by the hydrogen clearance technique, which is used to estimate blood flow in the retina. The first model assumes that the retina consists of three, well-mixed layers with different thickness, and the second is a two-dimensional model consisting of three regions that represent the layers in the retina. Diffusion between the layers and leakage through the outer edges are considered. Solutions to the governing equations are obtained by employing Fourier series and finite difference methods for the two models, respectively. The effect of important parameters on the hydrogen concentration is examined and discussed. The results contribute to understanding the dispersal of hydrogen in the retina and in particular the effect of flow in the vascular retina. It is shown that the predominant features of the process are captured by the simpler model.   doi: https://doi.org/10.1017/S144618112200005