Search

This study offers a comprehensive understanding of the most important geometrical concepts for concave shape particles with very low sphericity. Study of concave hulls in three-dimensional space is performed with an emphasis on accurate and asymptotically fast algorithms. Based on that a three-dimensional concave hull algorithm is designed to generate the actual shape of irregular particles through a set of 3D surface coordinate data points captured by 3D handy laser scanner and photogrammetry. The algorithm is utilized for a wide range of large-scale waste tyre and rock aggregates to assess several fundamental theoretical hypotheses related to geometric parameters, including surface texture with concavity/convexity, concave hull volume, perimeters of projected area, and concavity computation that have not been tested before for highly irregular concave shape particles. As a result, the morphological characteristics of the waste-tyre-stabilized rock aggregate mixtures are analysed for mining operations. We also provide the details on how the application of the resulting particle morphology is employed in cloning particles with wide range of concavity distribution. The paper identifies the accuracy by implementing the proposed 3D concave hull algorithm for morphology analysis of concave particles and comparing the morphology analysis results against those of Finite Element Method (FEM), polar representation approach (PRA), and experimental data. [Display omitted] • Design of 3D concave hull algorithm for morphology of concave-shape particles. • Algorithm promotes advanced 3D geometric features of highly concave aggregates. • It is substantially faster than FEM and PRA for processing of 3D geometric datasets. • It approximates actual surface area of irregular concave particles with high accuracy. • The attained precision is comparable to the experimental data. [ABSTRACT FROM AUTHOR]

This study investigates the impact of buoyancy on the mixing and flame structure of hydrogen jet diffusion flames. A validated Computational Fluid Dynamics (CFD) model for hydrogen diffusion flames is developed, employing the k − ω turbulence model and a steady flamelet combustion model. By accounting for the buoyancy term, the model accurately predicts the stoichiometric hydrogen flame length within a mere 0.2% deviation from the experimental value. In contrast, excluding the buoyancy term leads to a prediction divergence of around 5%. Deeper analysis of the mixture fraction field indicates that buoyancy enhances mixing in the flame's far-field region, facilitating a more rapid dilution of the fuel stream within the air. This, in turn, results in a shorter flame. The scope of the modelling is expanded to encompass buoyancy effects on hydrogen flames with jet Reynolds numbers (R e J ) up to 15,000. While the buoyancy's influence on flame control weakens as R e J increases, a noticeable ∼ 4% variation in stoichiometric flame length persists between scenarios with and without buoyancy. • Accounting for buoyancy enhances H 2 flame prediction accuracy in CFD simulations. • Buoyancy boosts fuel-air mixing; its impact on reaction kinetics is negligible. • Buoyancy effect weakens with increasing jet velocity, but remains noticeable. [ABSTRACT FROM AUTHOR]