Using CFD to improve the design of a circulating water channel

Computational Fluid Dynamics (CFD) has been used as a design tool to investigate means of improving flow uniformity in the working section of a circulating water channel. The CFD model was based on a 1/10th scale wind-tunnel model of the circulating water channel at the Australian Maritime Hydrodynamics Research Centre (AMHRC). The CFD analysis was compared with experimental results obtained from the wind-tunnel model to validate the use of the CFD model. Three changes to the design were investigated; alteration of turning vane angle, increased resistance coefficient of a honeycomb screen and addition of trailing edge extensions to the turning vanes. The turning vane angle changes resulted in little improvement in flow uniformity. Increasing the resistance coefficient of the honeycomb screen resulted in improved uniformity, but at the expense of increased pressure loss. The addition of trailing edge extensions to the turning vanes resulted in the most significant improvements in flow uniformity. These results will be useful in selecting improvements to the circulating water channel

The Effect of Gomphonema and Filamentous Algae Streamers on Hydroelectric Canal Capacity and Turbulent Boundary Layer Structure

Gomphonema, a freshwater diatom, is currently being studied to determine its effect on the capacity of hydroelectric canals and the structure of turbulent boundary layers. Gomphonema is the primary fouling organism present in Tarraleah No.1 Canal (operated by Hydro Tasmania) and was found to cause a 10% reduction in flow carrying capacity. Filamentous algae streamers up to 200mm long have also been observed in the canal. A recirculating water tunnel was used to measure the characteristics of the boundary layer flow over a 997mm x 597mm test plate covered with a biofilm grown in the field in an attempt to better understand the mechanisms for the increase in drag. Mean velocity profiles for the fouled test plate have been compared with results for a smooth test plate

Design and Calibration of a Facility for Film Cooling Research

An existing open circuit wind tunnel has been modified to incorporate a secondary supply loop to provide controlled flow conditions at the inlet to a film cooling hole model. The primary or crossflow fluid enters from atmosphere through a smooth two-dimensional contraction before entering the working section. The newly constructed supply loop has a single inlet from a high pressure source, in-line blower, and a 600mm long rectangular passage working section. Various film cooling geometries can be installed to connect the supply loop passage to the main wind tunnel working section. The installation of the supply loop enables variation of cooling hole inlet conditions, including crossflow velocity, mass flow rate, and flow direction. Detailed flow measurements were made to establish uniformity of flow in the supply passage and accurate control of coolant mass flow. A range of operating conditions have been established and calibrated for use in subsequent research

A Numerical Study of the Flow through a Safety Butterfly Valve in a Hydro-Electric Power Scheme

A numerical study of the flow through a safety butterfly valve used in a hydro-electric power scheme to stop water supply to a downstream penstock is reported. Computational fluid dynamics applied in a quasi-steady manner is used to predict the hydrodynamic torque versus opening angle characteristic during a constant head test. Factors influencing these results, such as Reynolds number and unsteady flow effects, are found to be significant. The predicted results are compared with field measurements of the full-size valve. Issues associated with applying the numerical results to predict valve characteristics at higher Reynolds numbers are discussed. Further computational and experimental studies are recommended

A Force Balance to Measure the Total Drag of Biofilms on Test Plates

A floating force balance has been designed and integrated into the working section of a to enable the measurement of total drag on test plates, which form part of the tunnel wall. Measurements completed include a calibration of the rig using a smooth acrylic plate, a smooth painted plate, and an artificially roughened plate. The painted plate and rough plate have also been studied with biofilms attached to their surface. The water tunnel and total drag rig have been built specifically to allow the detailed investigation of freshwater biofilm effects have on the flow through hydraulic conduits. Calibration results show that useful information can be obtained by using the force balance, particularly in association with other measurement techniques. Research into the effects of biofilms showsthat large increases in friction and effective roughness can be expected

The dynamics of ovine gastrointestinal nematode infections within ewe and lamb cohorts on three Scottish sheep farms

Gastrointestinal nematodes (GIN) are a serious concern for sheep producers worldwide. However, there is a paucity of evidence describing the epidemiology of GIN on modern UK sheep farms. The aim of this paper was to understand whether expected seasonal variations of infection are still found in ewes and lambs under varying management strategies in temperate climates. Faecal egg counts (FEC) were conducted on freshly voided samples collected from groups of ewes and lambs every third week for twelve months on three farms in southeast Scotland. The patterns of egg output have been described here in relation to management practices undertaken on the farms. Despite changes in farming practice and climatic conditions, the findings complement historical studies detailing the epidemiology of GIN. Findings include a periparturient rise in ewe FEC on two of the farms, while lambing time treatment appeared to suppress this on the third farm. On the same two farms lamb FEC increased during the summer, reaching a peak in the autumn. The work also highlights how the ad hoc use of anthelmintics does little to impact these patterns

Time-lapse mesoscopy of Candida albicans and Staphylococcus aureus dual-species biofilms reveals a structural role for the hyphae of C. albicans in biofilm formation

Polymicrobial infection with Candida albicans and Staphylococcus aureus may result in a concomitant increase in virulence and resistance to antimicrobial drugs. This enhanced pathogenicity phenotype is mediated by numerous factors, including metabolic processes and direct interaction of S. aureus with C. albicans hyphae. The overall structure of biofilms is known to contribute to their recalcitrance to treatment, although the dynamics of direct interaction between species and how it contributes to pathogenicity is poorly understood. To address this, a novel time-lapse mesoscopic optical imaging method was developed to enable the formation of C. albicans/S. aureus whole dual-species biofilms to be followed. It was found that yeast-form or hyphal-form C. albicans in the biofilm founder population profoundly affects the structure of the biofilm as it matures. Different sub-populations of C. albicans and S. aureus arise within each biofilm as a result of the different C. albicans morphotypes, resulting in distinct sub-regions. These data reveal that C. albicans cell morphology is pivotal in the development of global biofilm architecture and the emergence of colony macrostructures and may temporally influence synergy in infection.</p

A loop-mediated isothermal amplification (LAMP) assay to identify isotype 1 β-tubulin locus SNPs in synthetic double-stranded Haemonchus contortus DNA

Development of sustainable gastrointestinal nematode (GIN) control strategies depends on the ability to identify the frequencies of drug-susceptible and resistant genotypes in GIN populations arising from management practices undertaken on individual farms. Resistance to BZ drugs in GINs has been shown to be conferred by the presence of defined SNPs in the isotype 1 β-tubulin locus. Loop-mediated isothermal amplification (LAMP) assays are amenable to use on a range of DNA templates and are potentially adaptable to use in practical, cost-effective, pen-side diagnostic platforms that are needed to detect anthelmintic resistance in the field. In this study, we designed primers and examined LAMP assays to detect each of the three major isotype 1 β-tubulin SNPs conferring genetic susceptibility to BZ drugs. We used artificial pools of synthetic DNA, containing different proportions of susceptible and resistant SNPs to determine reproducibility of the assays. We demonstrated the detection of each of the isotype 1 β-tubulin SNPs conferring susceptibility to BZ drugs using the optimal LAMP assay. Isotype 1 β-tubulin SNP typing was effective in detecting BZ susceptibility, but the accuracy was reduced in samples with less than 60 % susceptible DNA. Our results show the potential for LAMP SNP typing to detect genetic susceptibility or resistance to anthelmintic drugs in livestock GINs, and some of the limitations in our approach that will need to be overcome in order to evaluate this assay using field samples. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12639-021-01414-w

A quantitative analysis of attitudes and behaviours concerning sustainable parasite control practices from Scottish sheep farmers

Nematode control in sheep, by strategic use of anthelmintics, is threatened by the emergence of roundworms populations that are resistant to one or more of the currently available drugs. In response to growing concerns of Anthelmintic Resistance (AR) development in UK sheep flocks, the Sustainable Control of Parasites in Sheep (SCOPS) initiative was set up in 2003 in order to promote practical guidelines for producers and advisors. To facilitate the uptake of ‘best practice’ approaches to nematode management, a comprehensive understanding of the various factors influencing sheep farmers’ adoption of the SCOPS principles is required. A telephone survey of 400 Scottish sheep farmers was conducted to elicit attitudes regarding roundworm control, AR and ‘best practice’ recommendations. A quantitative statistical analysis approach using structural equation modelling was chosen to test the relationships between both observed and latent variables relating to general roundworm control beliefs. A model framework was developed to test the influence of socio-psychological factors on the uptake of sustainable (SCOPS) and known unsustainable (AR selective) roundworm control practices. The analysis identified eleven factors with significant influences on the adoption of SCOPS recommended practices and AR selective practices. Two models established a good fit with the observed data with each model explaining 54% and 47% of the variance in SCOPS and AR selective behaviours, respectively. The key influences toward the adoption of best practice parasite management, as well as demonstrating negative influences on employing AR selective practices were farmer’s base line understanding about roundworm control and confirmation about lack of anthelmintic efficacy in a flock. The findings suggest that improving farmers’ acceptance and uptake of diagnostic testing and improving underlying knowledge and awareness about nematode control may influence adoption of best practice behaviour