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Arc welding is a thermal plasma process widely used to join metals. An arc welding model that couples fluid dynamic and electromagnetic equations was initially developed as a research tool. Subsequently, it was applied to improve and optimise industrial implementations of arc welding. The model includes the arc plasma, the electrode, and the workpiece in the computational domain. It incorporates several features to ensure numerical accuracy and reduce computation time and memory requirements. The arc welding code has been refactored into commercial-grade Windows software, ArcWeld, to address the needs of industrial customers. The methods used to develop ArcWeld and its extension to new arc welding regimes, which used the Workspace workflow platform, are presented. The transformation of the model to an integrated software application means that non-experts can now run the code after only elementary training. The user can easily visualise the results, improving the ability to analyse and generate insights into the arc welding process being modelled. These changes mean that scientific progress is accelerated, and that the software can be used in industry and assist welders' training. The methods used are transferrable to many other research codes. [ABSTRACT FROM AUTHOR]

Our recent continuum theory for stress-gradient-induced migration of polymers in confined solutions, including the depletion from the solid boundaries [Hajizadeh, E., and R. G. Larson, Soft Matter, 13, 5942–5949 (2017)], is applied to a two-dimensional rotational shearing flow in the gap between eccentric cylinders. Analytical results for the steady-state distribution of polymer dumbbells in the limit of dilute polymer solution c / c ∗ ≪ 1 (c∗ is the chain overlap concentration) and in the absence of hydrodynamic interactions are obtained. The effects of eccentricity e and of three perturbation variables, namely, Weissenberg number W i , gradient number G d (which defines the level of polymer chain confinement), and Péclet number P e on the polymer concentration pattern, are investigated. The stress-gradient-induced migration results in polymer migration toward the inner cylinder, while wall-depletion-induced migration results in near-zero polymer concentration close to flow boundaries, which couples to a stress-gradient-induced migration effect. In the presence of wall-depletion, we obtain first order concentration variation proportional to W i. However, in the absence of wall-depletion, there is no first order contribution and, therefore, the lowest-order concentration variation is proportional to W i 2. An upper limit of W i = 1.6 exists, beyond which the numerical solution demands an excessive under-relaxation to converge. In addition, for a high degree of polymer chain confinement, i.e., for G d greater than 0.5, the continuum theory fails to be accurate and mesoscopic simulations that track individual polymer molecules are needed. [ABSTRACT FROM AUTHOR]

A numerical investigation has been conducted to model the cement flow behaviour associated with a full-scale industrial air-slide conveyor (ASC) system. Steady-state simulations on the ASC were performed to predict its operational and the cement flow characteristics, and comparisons with actual operational data of the ASC demonstrate satisfactory agreement. Subsequently, hopper input loading, velocity as well as the suction fan pressure were varied and simulated to identify how cement conveying capacity by the ASC may be increased. Simulation results indicate that an increase in air chamber pressure leads to a corresponding increase in conveying capacity because of the enhanced capability of air chamber to sustain the cement flow, whereas increasing hopper input velocity and suction fan pressure both lead to lower demands in the air chamber pressure required to sustain existing conveying capacity. Detailed results associated with the cement and air flow mixture behaviour within the ASC reveal that, while the cement and air mixture flow is highly complex and three-dimensional, gross trends between the various operational parameters can be isolated successfully and may offer insights into how the existing ASC may be modified to increase conveying capacity. [ABSTRACT FROM AUTHOR]

Purpose – This paper aims to validate and analyse the NASA35 axial compressor performance based on a numerical approach. Design/methodology/approach – Knowledge about flow property change during compressor operation at high and relatively low speed is still limited. This work provides a numerical approach to address these problems. Validation of numerical methods is proposed to generate confidence the numerical approach adopted, and after that, analysis of compressor performance at different operation conditions is carried out. Findings – The numerical methods proposed are proved capable in predicting compressor performance. Changes of flow property during compressor operation are discussed and explained. Research limitations/implications – The current numerical work is carried out based on the first stage of the NASA35 axial compressor, where the interactive effects from adjacent stage are not counted in. Furthermore, the steady-state simulation enforces an averaging of flow at rotor-stator interface, where the transient rotor-stator interaction is removed. Practical implications – This work validates the numerical methods used in the prediction of NASA35 axial compressor performance, and a similar numerical approach can be used for other turbomachinery simulation cases. Originality/value – This work reinforces the understanding of axial compressor operation and provides reliable results for further investigation of a similar type of compressor. In addition, details of flow field within the NASA35 compressor during operation are given and explained which experiments still have difficult to achieve. [ABSTRACT FROM AUTHOR]