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Khayyer, Abbas,Gotoh, Hitoshi,Falahaty, Hosein,Shimizu, Yuma,Nishijima, Yusuke Techno-Press 2017 Ocean systems engineering Vol.7 No.3
The paper aims at illustrating several key issues and ongoing efforts for development of a reliable fully-Lagrangian particle-based solver for simulation of hydroelastic slamming. Fluid model is founded on the solution of Navier-Stokes along with continuity equations via an enhanced version of a projection-based particle method, namely, Moving Particle Semi-implicit (MPS) method. The fluid model is carefully coupled with a structure model on the basis of conservation of linear and angular momenta for an elastic solid. The developed coupled FSI (Fluid-Structure Interaction) solver is applied to simulations of high velocity impact of an elastic aluminum wedge and hydroelastic slammings of marine panels. Validations are made both qualitatively and quantitatively in terms of reproduced pressure as well as structure deformation. Several remaining challenges as well as important key issues are highlighted. At last, a recently developed multi-scale MPS method is incorporated in the developed FSI solver towards enhancement of its adaptivity.
Shimizu, Yuma,Khayyer, Abbas,Gotoh, Hitoshi Techno-Press 2022 Ocean systems engineering Vol.12 No.1
A refined projection-based purely Lagrangian meshfree method is presented towards reliable numerical analysis of fluid flow interactions with saturated/unsaturated porous media of uniform/spatially-varying porosities. The governing equations are reformulated on the basis of two-phase mixture theory with incorporation of volume fraction. These principal equations of mixture are discretized in the context of Incompressible SPH (Smoothed Particle Hydrodynamics) method. Associated with the consideration of governing equations of mixture, a new term arises in the source term of PPE (Poisson Pressure Equation), resulting in modified source term. The linear and nonlinear force terms are included in momentum equation to represent the resistance from porous media. Volume increase of fluid particles are taken into consideration on account of the presence of porous media, and hence multi-resolution ISPH framework is also incorporated. The stability and accuracy of the proposed method are thoroughly examined by reproducing several numerical examples including the interactions between fluid flow and saturated/unsaturated porous media of uniform/spatially-varying porosities. The method shows continuous pressure field, smooth variations of particle volumes and regular distributions of particles at the interface between fluid and porous media.
Hwang, Sung-Chul,Khayyer, Abbas,Gotoh, Hitoshi,Park, Jong-Chun Elsevier 2014 Journal of fluids and structures Vol.50 No.-
<P><B>Abstract</B></P> <P>A fully Lagrangian particle-based method is developed for simulating the FSI (Fluid–Structure Interaction) problems corresponding to incompressible fluid flows and elastic structures. First, the developed elastic structure model is verified by static and dynamic tests corresponding to a simple cantilever beam. The simulation results are compared with analytical and other researchers׳ numerical solutions. Then, the structure model is carefully coupled with a fluid model comprising of the so-called PNU-MPS (Pusan-National-University-modified Moving Particle Simulation) method and several recently developed enhanced schemes. The coupled fluid–structure method is applied to a dam break with an elastic gate and a violent sloshing flow with a hanging rubber baffle. The results of simulations are compared with those of the experiments by Antoci et al. (2007) and Idelsohn et al. (2008).</P> <P><B>Highlights</B></P> <P> <UL> <LI> A fully Lagrangian particle-based method is developed for FSI simulations. </LI> <LI> A mathematically-physically consistent coupling algorithm is proposed. </LI> <LI> A set of enhanced schemes and appropriate modifications are applied. </LI> <LI> Verifications are performed to show the robustness of the developed method. </LI> </UL> </P>
SPH simulation of solitary wave interaction with coastal structures
Cai, Guozhen,Luo, Min,Wei, Zhaoheng,Khayyer, Abbas Techno-Press 2022 Ocean systems engineering Vol.12 No.3
This paper adopts the Smoothed Particle Hydrodynamics (SPH) open-source code SPHinXsys to study the solitary wave interaction with coastal structures. The convergence properties of the model in terms of particle size and smoothing length are tested based on the example of solitary wave propagation in a flat-bottom wave flume. After that, the solitary wave interactions with a suspended submerged flat plate and deck with girders are studied. The wave profile and velocity field near the surface of the structures, as well as the wave forces exerted onto the structures are analyzed.
An improved solid boundary treatment for waveefloat interactions using ISPH method
Xing Zheng,Xipeng Lv,Qingwei Ma,Wenyang Duan,Abbas Khayyer,Songdong Shao 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.3
The Smoothed Particle Hydrodynamics (SPH) method has proved to have great potentials in dealing with the wave-structure interactions. Compared with the Weakly Compressible SPH (WCSPH) method, the ISPH approach solves the pressure by using the pressure Poisson equation rather than the equation of state. This could provide a more stable and accurate pressure field that is important in the study of wave-structure interactions. This paper improves the solid boundary treatment of ISPH by using a high accuracy Simplified Finite Difference Interpolation (SFDI) scheme for the 2D wave-structure coupling problems, especially for free-moving structure. The proposed method is referred as the ISPH_BS. The model improvement is demonstrated by the documented benchmark tests and laboratory experiment covering various wavestructure interaction applications.
An improved solid boundary treatment for wave-float interactions using ISPH method
Zheng, Xing,Lv, Xipeng,Ma, Qingwei,Duan, Wenyang,Khayyer, Abbas,Shao, Songdong The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.3
The Smoothed Particle Hydrodynamics (SPH) method has proved to have great potentials in dealing with the wave-structure interactions. Compared with the Weakly Compressible SPH (WCSPH) method, the ISPH approach solves the pressure by using the pressure Poisson equation rather than the equation of state. This could provide a more stable and accurate pressure field that is important in the study of wave-structure interactions. This paper improves the solid boundary treatment of ISPH by using a high accuracy Simplified Finite Difference Interpolation (SFDI) scheme for the 2D wave-structure coupling problems, especially for free-moving structure. The proposed method is referred as the ISPH_BS. The model improvement is demonstrated by the documented benchmark tests and laboratory experiment covering various wave-structure interaction applications.