Modelling incompressible flows and fluid-structure interaction problems with smoothed particle hydrodynamics: Briefing on the 2017 SPHERIC Beijing International Workshop *

Mou-bin Liu(劉謀斌), Can Huang(黃燦), A-man Zhang(張阿漫)

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Modelling incompressible flows and fluid-structure interaction problems with smoothed particle hydrodynamics: Briefing on the 2017 SPHERIC Beijing International Workshop*

Mou-bin Liu1(劉謀斌), Can Huang2(黃燦), A-man Zhang3(張阿漫)

1.2.3.

The 2017 SPHERIC Beijing International Workshop (or SPHERIC Beijing 2017) was held at Peking University, in China, on October 17-20, 2017. This is the first time that the SPHERIC Workshop was held out ofEurope. We are delighted to present nine contributions in this Special Column of the Journal of Hydrodynamics, and take this opportunity to announce that the 13th SPHERIC Workshop (or SPHERIC 2018) will be held in Galway, Ireland in 2018 by the National University of Ireland, and the SPHERIC International Workshop in Harbin, China in 2019 by the Harbin Engineering University.

Smoothed particle hydrodynamic (SPH), SPHERIC, free surface flows, meshfree methods, particle method

Introduction

Viscous incompressible flows in ocean and coas- tal hydrodynamics and offshore engineering are signi- ficantly important. Typical viscous incompressible flow phenomena include wave dynamics (waver generation, wave breaking, and wave interaction with other structures), dam breaking, water filling and water discharge (to and from a water tank or reservoir), shallow water flows, entry and exit of water, sloshing phenomena with fluid-solid interaction, and many different other problems. Due to such special features, these flow phenomena are usually difficult for theore- tical analyses. Furthermore, experiments of these flows are usually expensive and inconvenient, especi- ally for large or even full scale models.

Over the past few decades, with the development of numerical technique, CFD technique has been widely adopted in a variety of engineering applica- tions involving the fields of hydrodynamics and ocean engineering. Grid-based methods have difficulties solving problems with large deformation and free surface flows, such as rapid movement of solid objects, violent fluid-solid interaction, change and breakup of free surfaces, and wave breaking and impacting. Generally, classical grid-based methods, such as the finite difference method (FDM) and finite element method (FEM), require expensive re-meshing algori- thms or dynamic overlapping grids to avoid severe mesh distortions and associated errors. Besides, special techniques are usually used to treat the free surface, such as the level set (LS) function, the volume of fluid (VOF) and the constrained interpola- tion profile (CIP).

Recently, meshfree and particle methods have been applied in viscous incompressible flows with large deformation and free surface. Because of their mesh-less features, meshfree and particle methods are inherently well-suited for the analysis of problems with large deformation and free surface, and have been considered as the next generation computational methods. Popular meshfree and particle methods include moving particle semi-implicit (MPS), material point method (MPM), finite volume particle method (FVPM), reproducing kernel particle method (RKPM), element free Galerkin (EFG), dissipative particle dynamics (DPD) and the smoothed particle hydrody- namics (SPH).

SPH is a most popular meshfree, Lagrangian, particle method with some attractive features, and has gained wide attention in the area of scientific com- puting. In SPH, the field variables (such as density, velocity, acceleration) can be obtained through appro- ximating the governing equations which are discre- tized on the set of particles. Exemplary applications refer to the development of galaxies in astrophysics, environmental engineering, applied solid mechanics, marine and coastal engineering, nuclear power engi- neering, and medical engineering or geotechnical problems. Due to its meshfree, Lagrangian and parti- cle nature, SPH has been attracting more and more researchers in modeling viscous incompressible flows, especially those in the fields of hydrodynamics and ocean engineering.

1. SPHERIC International Workshop

SPHERIC, or “SPH European Research Interest Community”, is an international organization repre- senting the community of researchers and industrial users of smoothed particle hydrodynamics. It was founded in 2005 as a Special Interest Group of the ERCOFTAC community. Since then, the SPHERIC community continues both to grow and to play an important role in helping the development of SPH for academia, industry and government organizations. The successful concept of SPHERIC is due to a methodological focus in an interdisciplinary applica- tion environment, integrating the know-how of physicists, mathematicians, IT experts and engineers from academia and industry.

The SPHERIC workshops are the only world- wide events which exclusively focus on the SPH me- thodology and related simulation approaches. Follo- wing the impulse generated by a collection of initia- tives in 2005 (France, UK, Italy×××), a need to foster and collaborate efforts and developments was identi- fied. Since then, the SPHERIC organization has gone on to push the development of the SPH method forward providing a network of researchers and industrial users around the world as a means to com- municate and collaborate. The overarching aim of SPHERIC workshops is to promote the SPH method in both academic and industrial fields, enhance colla- borations between countries and institutes, encourage and facilitate the spread of the SPH method through- out the wider international community. For more information about SPHERIC, please visit http:// spheric-sph.org.

2. SPHERIC Beijing 2017

The 2017 SPHERIC Beijing International Work- shop(or SPHERIC Beijing 2017) is held at PekingUniversity, a top university in China, on October 17-20, 2017. This is the first time that theSPHERIC Workshop is held in Asia.

This workshop includes following five topics:

(1)Computational modelling using SPH. Diversi- fied numerical models, including free surface and moving boundaries, solids and structures, multiple continua and multi-phase flows, viscosity and turbu- lence, incompressible flows and complex physics, are developed to solve various scientific and engineering problems.

(2) Theoretical and numerical aspects. Conver- gence, stability, boundary and adaptivity of SPH are important to enhance the theoretical foundation and its reliability.

(3)Numerictechnologies.High-performance co- mputing, hardware acceleration, and pre-processing and visualization techniques are very critical aspects for complex and practical applications in engineering and sciences.

(4)Alternative formulations and particle-based simulation techniques. Alternative meshless particle methods, such as material point method, finite volume particle method, reproducing kernel particle method, physics evoked cloud method, possess many similari- ties, enrich big family of meshfree, particle methods and are therefore helpful for the development of SPH.

(5)Diversified SPH applications. These applica- tions include hydraulic engineering, ocean enginee- ring, impact engineering, environmental engineering, geotechnical engineering and even bioengineering.

Apart from the regular workshop, we also organized a one-day training course. The training course focuses on theory and principles of SPH and practical hands-on programming. The aim of the training courses is to provide learning opportunities for young researchers who are beginning their work in the field. Also, the training day is a useful opportunity for more experienced SPH developers and users to share their insights and ideas.

In total, 130 delegates from China, France, Germany, UK, Italy, Spain, Switzerland, Ireland, USA, Japan and Australia attended the conference. 56 abstracts were selected to present in the SPHERIC Beijing 2017, while 43 of them were included in the conference proceedings. The full conference procee- dings are available through the website at http://www. sci-en-tech.com. The two keynote speakers are Prof. David Le Touzé from Ecole Centrale de Nantes, France and Prof. J. S. Chen from University of California at San Diego, USA.

3. Continuing collaboration with Journal of Hydro- dynamics

We highly appreciate that the Journal of Hydro- dynamics agrees to publish nine conference papers from the 2017 SPHERIC Beijing International Work- shop, after substantial expansion and revision. In the past decades, the SPH method has been developed rapidly in the field of computational engineering sciences, especially in the simulations of highly dis- torting fluids including free-surface flows, breaking waves, and fluid-structure interaction where mesh- based methods may be difficult. These papers present diversified numerical models and address practical and realistic applications in hydrodynamics and ocean engineering. We hope that these papers will help push the development of the SPH method and extend the SPH method into more complex and practical applica- tions in engineering and sciences.

The Journal of Hydrodynamics reflects a broad range of research activities in the fields of hydrody- namics and ocean engineering. The Journal offers a platform for exchanging ideas and experiences, and promoting the cutting-edge development of hydro- dynamic research and its applications. We share the same view with the journal that multidisciplinary research breeds innovation and advancement of traditional research subjects, and we attach great importance to our collaboration with this distingui- shed Journal. We are proud that the Chair of the SPHERIC Beijing 2017, Prof. Mou-bin Liu from Peking University, and two Co-Chairs, Prof. A- man Zhang from Harbin Engineering University, and Li Zou from Dalian University of Technology all serve on the Editorial board of the Journal of Hydrody- namics. We appreciate the support from the Journal of Hydrodynamics and will continue to recommend high quality papers from the SPH research community to the journal.

Acknowledgement

Support fromthe Beijing Innovation Centre for Engineering Science and Advanced Technology (BIC- ESAT) is highly appreciated.

[1] Marrone S., Colagrossi A., Chiron L. et al. High speed water impacts of fat plates in different ditching con- figurations through a Riemann-ALE SPH model [C]., Beijing, China, 2017, 1-9.

[2] Khayyer A., Gotoh H., Shimizu Y. et al. An enhanced ISPH-SPH coupled method for incompressible fluid- elastic structure interactions [C].,Beijing, China, 2017, 23-29.

[3] Han L., Hu X. SPH modeling of fluid-structure inte- raction [C].,Beijing, China, 2017, 30-36.

[4] Rao C. P., Wan D. C. Investigation of interaction between solitary wave and horizontal plate based on MPS-FEM coupled method [C].,Beijing, China, 2017, 37-42.

[5] Sun Z. G., Ni N., Sun Y. J. et al. Modeling of single film bubble and numerical study of the Plateau structure in foam system [C].,Beijing, China, 2017, 63-70.

[6] González-Cao J., García-Feal O., Crespo A. J. C. et al. Analysis of the hydrological safety of dams using numeri- cal tools: Iber and DualSPHysics [C].,Beijing, China, 2017, 199-205.

[7] Zhang F., Shang S. P., Crespo A. J. C. et al. DualSPHysics: A numerical tool to simulate real breakwaters [C].,Beijing, China, 2017, 228-235.

[8] De Padova D., Mossa M., Sibilla S. SPH numerical inves- tigation of oscillating characteristics of hydraulic jumps at an abrupt drop [C].,Beijing, China, 2017, 9-14.

[9] Rentschler M., Marongiu J. C., Neuhauser M. et al. Over- view of SPH-ALE applications for hydraulic turbines in ANDRITZ Hydro [C].,Beijing, China, 2017, 285-292.

(November 9, 2017, Accepted November 19)

?China Ship Scientific Research Center 2018

* Project supported by the National Natural Science Foundation of China (Grant Nos. 11742012, 51779003 and U1530110)

Mou-bin Liu (1970-), Male, Ph. D., Professor

Mou-bin Liu,

E-mail: mbliu@pku.edu.cn