PhD in Computational Fluid Dynamics

MINIMAL - sMoothed partIcle hydrodyNamIcs for MultiphAse fLow

Multiphase flows are encountered in most physical processes and engineering applications. The present project will look at the physics of the wave breaking at the beach, where the wave energy is dissipated generating air entrapment, and significant sediment transport. A common occurrence in the above-mentioned phenomena is the multiphase and often complex flows which current state-of-the-art in numerical simulations and modelling either use ad-hoc methodologies or choose not to model explicitly.

Indeed, formulating a general multiphase methodology which spans across different physical processes poses a great modelling challenge. This is particularly true when looking the capabilities of classical numerical discretisation schemes, which have been intended to excel in bounded domains with some a priori knowledge of the area of significance. On the other hand, schemes which are based on particle (instead of mesh) methods, alleviate this problem of severe deformation, multiple continua, and fragmentation of the continua interface in bounded or free surface flows [1].

A well-known particle numerical scheme is smoothed particle hydrodynamics (SPH). SPH has demonstrated several advantages when comparing to traditional schemes due to the Lagrangian formulation. Nevertheless, and despite the recent advances in modelling multiphase flows [2] having a sharp interface between the phases, issues such as high-density ratios between phases, numerical stability, accuracy, and automatic node refinement, still remain elusive [3].

Herein, we propose to develop, in close collaboration between the researchers of the University of Manchester, a new approach for SPH to ensure continuity at the interface while maintaining a sharp interface between phases in the framework of the DualSPHysics open-source code (https://dual.sphysics.org/ ). Stability and consistency will be addressed by using shock-capturing techniques [4] and will further develop the new iterative implicit shifting [5] pioneered by Parma, Manchester and other collaborators which provides groundbreaking advances for the convergence of the SPH scheme. The aim is to create a SPH based formulation which from a discretisation perspective is applicable to gas-liquid-solid phases irrespectively of the physics involved in the aforementioned phases.

The main objective of the research project is the development of a new SPH multiphase formulation capable to simulate the wave breaking at the beach, including air and sediment transport phenomena.

Working group:

Prof. Renato Vacondio, University of Parma (UniPr). PhD student recruited for the project by UniPr, Prof. Benedict Rogers and Dr. George Fourtakas, University of Manchester (UoM).

The research group involved in the project (Dr. Renato Vacondio – UniPr and Dr. Prof. Benedict Rogers and Dr. George Fourtakas, UoM) have a long-standing collaboration that spans more than a decade. Indeed, this is a very successful collaboration with more than 10 papers in international Q1 journals and dozens of conference publications.

Further, they are co-developers of the open source DualSPHysics (https://dual.sphysics.org/ ) solver, a collaboration that has been extremely successful with a state-of-the-art solver that has more than 100k downloads and is being used by industry and academia alike.

References:

[1]. Violeau, D. and B.D. Rogers, Smoothed particle hydrodynamics (SPH) for free-surface flows: past, present and future. Journal of Hydraulic Research, 2016. 54(1): p. 1-26.

[2]. Fourtakas, G. and B. Rogers, Modelling multi-phase liquid-sediment scour and resuspension induced by rapid flows using Smoothed Particle Hydrodynamics (SPH) accelerated with a Graphics Processing Unit (GPU). Advances in Water Resources, 2016. 92: p. 186-199.

[3]. Vacondio, R., C. Altomare, M. De Leffe, X. Hu, D. Le Touzé, S. Lind, J.-C. Marongiu, S. Marrone, B.D. Rogers, and A. Souto-Iglesias, Grand challenges for Smoothed Particle Hydrodynamics numerical schemes. Computational Particle Mechanics, 2021. 8(3): p. 575-588.

[4]. Rezavand, M., C. Zhang, and X. Hu, A weakly compressible SPH method for violent multi-phase flows with high density ratio. Journal of Computational Physics, 2020. 402: p. 109092.

[5]. Rastelli, P., R. Vacondio, J. Marongiu, G. Fourtakas, and B.D. Rogers, Implicit iterative particle shifting for meshless numerical schemes using kernel basis functions. Computer Methods in Applied Mechanics and Engineering, 2022. 393: p. 114716.

[6]. Vacondio, R., B. Rogers, P.K. Stansby, P. Mignosa, and J. Feldman, Variable resolution for SPH: a dynamic particle coalescing and splitting scheme. Computer Methods in Applied Mechanics and Engineering, 2013. 256: p. 132-148.

[7]. Domínguez, J.M., G. Fourtakas, C. Altomare, R.B. Canelas, A. Tafuni, O. García-Feal, I. Martínez-Estévez, A. Mokos, R. Vacondio, and A.J. Crespo, DualSPHysics: from fluid dynamics to multiphysics problems. Computational Particle Mechanics, 2021: p. 1-29.