Accelerated numerical simulations of a heaving floating body by coupling a motion solver with a two-phase fluid solver

Brecht Devolder, Peter A Troch, Pieter Rauwoens

Research output: Contribution to journalArticle

Abstract

This paper presents a study on the coupling between a fluid solver and a motion solver to perform fluid–structure interaction (FSI) simulations of floating bodies such as point absorber wave energy converters heaving under wave loading. The two-phase fluid solver with dynamic mesh handling, interDyMFoam, is a part of the Computational Fluid Dynamics (CFD) toolbox OpenFOAM. The incompressible Navier–Stokes (NS) equations are solved together with a conservation equation for the Volume of Fluid (VoF). The motion solver is computing the kinematic body motion induced by the fluid flow. A coupling algorithm is needed between the fluid solver and the motion solver to obtain a converged solution between the hydrodynamic flow field around and the kinematic motion of the body during each time step in the transient simulation. For body geometries with a significant added mass effect, simple coupling algorithms show slow convergence or even instabilities. In this paper, we identify the mechanism for the numerical instability and we derive an accelerated coupling algorithm (based on a Jacobian) to enhance the convergence speed between the fluid and motion solver. Secondly, we illustrate the coupling algorithm by presenting a free decay test of a heaving wave energy converter. Thirdly and most challenging, a water impact test of a free falling wedge with a significant added mass effect is successfully simulated. For both test cases, the numerical results obtained by using the accelerated coupling algorithm are in a very good agreement with the experimental measurements.

Original languageEnglish (US)
JournalComputers and Mathematics with Applications
DOIs
StateAccepted/In press - Jan 1 2018
Externally publishedYes

Fingerprint

Fluid
Numerical Simulation
Fluids
Motion
Computer simulation
Added Mass
Kinematics
Converter
Dynamic Mesh
Incompressible Navier-Stokes
Numerical Instability
Convergence Speed
Absorber
Flow of fluids
Conservation
Energy
Wedge
Flow fields
Computational Fluid Dynamics
Computational fluid dynamics

Keywords

  • Accelerated coupling algorithm
  • CFD
  • Fluid–structure interaction
  • Rigid body heave motion
  • Two-phase flow

ASJC Scopus subject areas

  • Modeling and Simulation
  • Computational Theory and Mathematics
  • Computational Mathematics

Cite this

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title = "Accelerated numerical simulations of a heaving floating body by coupling a motion solver with a two-phase fluid solver",
abstract = "This paper presents a study on the coupling between a fluid solver and a motion solver to perform fluid–structure interaction (FSI) simulations of floating bodies such as point absorber wave energy converters heaving under wave loading. The two-phase fluid solver with dynamic mesh handling, interDyMFoam, is a part of the Computational Fluid Dynamics (CFD) toolbox OpenFOAM. The incompressible Navier–Stokes (NS) equations are solved together with a conservation equation for the Volume of Fluid (VoF). The motion solver is computing the kinematic body motion induced by the fluid flow. A coupling algorithm is needed between the fluid solver and the motion solver to obtain a converged solution between the hydrodynamic flow field around and the kinematic motion of the body during each time step in the transient simulation. For body geometries with a significant added mass effect, simple coupling algorithms show slow convergence or even instabilities. In this paper, we identify the mechanism for the numerical instability and we derive an accelerated coupling algorithm (based on a Jacobian) to enhance the convergence speed between the fluid and motion solver. Secondly, we illustrate the coupling algorithm by presenting a free decay test of a heaving wave energy converter. Thirdly and most challenging, a water impact test of a free falling wedge with a significant added mass effect is successfully simulated. For both test cases, the numerical results obtained by using the accelerated coupling algorithm are in a very good agreement with the experimental measurements.",
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