A hydrodynamic study of various obstacle shapes in 2D flow using SPH

The objective of this research is to analyze vortex structures, lift, and drag coefficients, generated by a variety of obstacles in the context of a 2D laminar flow, comparing the results between the different cases. To that aim, numerical simulations using the Smoothed Particle Hydrodynamics (SPH) method have been carried out. The resulting data presented herein constitute a comprehensive study of the flow around obstacle problem in 2D using SPH. The influence of the geometry on vortex formation has been studied at the Reynolds number Re = 100. The results show a strong agreement with the values in the literature for cylinders and squares. This is a crucial stage for the validation of the methodology before expansion to various geometries, e.g. square- cylinder combinations, piggybacks, and horizontal spoiler configurations. Notably, this study introduces a novel horizontal spoiler configuration, as opposed to the conventional vertical orientation found in the literature. To the best of the authors' knowledge, this configuration is presented here for the first time. Among single shapes, the cylinder with a spoiler exhibits the highest value for the drag coefficient, being 34% greater when compared to the single cylinder configuration. In addition, regarding configurations with a pair of side-by-side obstacles, the results indicate a notable increase in the drag coefficient for the case of a larger cylinder coupled with a smaller cylinder at the smallest gap amongst the ones tested. Having a look at the lift coefficient, the results for the different shapes oscillate considerably compared to the case of a single cylinder used as a reference. The maximum increase is obtained for the cylinder with spoiler (122%) and the piggyback at the minimum distance tested (135%), suggesting that objects in close proximity (or joined together) highly influence lift inception. Conversely, the greatest reduction in lift oscillations is found for the both the piggyback (58%) and the cylinder with a square (52%) when the gap between the two objects increases. In terms of the Strouhal number, the highest value is observed for the case of a single cylinder. For the other shapes tested, the Strouhal number is reduced from 11% to 63%. Therefore, the study allows to analyze the influence of different shapes on lift and drag forces, vortex shedding frequencies, and the relation amongst them, helping to understanding interference effects and shape influence, thus offering relevant insights to various engineering applications. The SPH method is validated using two of the geometries considered. In addition, a verification analysis is carried out in the case of the single cylinder considering lift and drag coefficients as well as Strouhal number. These studies (validation and verification) constitute a comprehensive convergence analysis - customary in CFD applications - for the proposed numerical scheme, confirming the accuracy of the SPH results for this particular problem. The simulations were carried out using the AQUAgpuSPH software, developed at Universidad Polit & eacute;cnica de Madrid (UPM).