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- Lorentzon, Johan, et al.
(författare)
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A numerical study of partitioned fluid-structure interaction applied to a cantilever in incompressible turbulent flow
- 2020
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Ingår i: International Journal for Numerical Methods in Engineering. - : Wiley. - 0029-5981 .- 1097-0207. ; 121:5, s. 806-827
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Tidskriftsartikel (refereegranskat)abstract
- This study presents an approach for partitioned fluid-structure interaction (FSI) applied to large structural deformations, where an incompressible turbulent solver is combined with a structural solver. The implementation is based upon two different open-source libraries by using MPI as a parallel communication protocol, the packages and OpenFOAM. FSI is achieved through a strongly-coupled scheme. The solver has been validated against cases with a submerged cantilever in a channel flow to which experiments, numerical calculations and theoretical solutions are available. The verification of the procedure is performed by using a solid-solid interaction (SSI) study. The solver has proven to be robust and has the same parallel efficiency as the fluid and the solid solver stand-alone.
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- Lorentzon, Johan, et al.
(författare)
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On stability and relaxation techniques for partitioned fluid-structure interaction simulations
- 2022
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Ingår i: Engineering Reports. - : Wiley. - 2577-8196. ; 4:10
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Tidskriftsartikel (refereegranskat)abstract
- The stability of relaxation techniques has been studied for strongly coupled fluid-structure interaction (FSI) with application to a cantilever immersed in channel flow. The fluid is governed by Navier–Stokes equations for incompressible flow condition using turbulence modeling, and the solid is governed by the equation of motion with compressible material modeling. The applied kinematic description is Lagrangian for the solid and Eulerian for the fluid. The coupling of the state solvers is achieved by the Arbitrary Lagrange–Euler procedure, which involves a mesh motion solver, and the FSI procedure is stabilized by relaxation. It is shown that the stability can be related to the frequency shift caused by FSI, and they follow the same rate for the shape factor of the structure with an offset. The results correlate well to theoretical results and show that all relaxations fail for sufficient high-frequency shift for given mesh resolution. We also propose a continuation technique to stabilize the solution near the instability region, which improves efficiency and can be integrated easily for the black-box FSI solution procedure.
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| 5. |
- Revstedt, Johan, et al.
(författare)
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Dynamic response and wake structures of cantilevers with square cross-section
- 2017
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Ingår i: National Conferenceon Computational Mechanics. - 9788494731112 ; , s. 7-19
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Konferensbidrag (refereegranskat)abstract
- The dynamic response of cantilevers to a hydrodynamic load has been studied numerically. The Reynolds number of the flow was fixed at 5000 and the variation in re-duced velocity was achieved by varying the Young’s modulus of the cantilever. Cantilevers with aspectratios of 5 and 10 were considered for reduced velocities in the range 2 to 30. The simulations were performed using a strongly coupled FSI tool based in the open source projects DEAL. IIand Open FOAM. The results show that as the eigenfrequency of the cantilever coincides with the vortex shedding frequency, the amplitude of the oscillation substantially increases, as expected. However, no desynchronization is observed for higher values of reduced velocity. Instead the amplitude remains fairly constant for the shorter cantilever and continuously increase for the longer one.
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| 6. |
- Al Sam, Ali, et al.
(författare)
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Evaluation of sub grid scale and local wall models in Large-eddy simulations of separated flow
- 2015
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Ingår i: 2nd Symposium on OpenFOAM® in Wind Energy. - : EDP Sciences. ; 5
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Konferensbidrag (refereegranskat)abstract
- The performance of the Sub Grid Scale models is studied by simulating a separated flow over a wavy channel. The first and second order statistical moments of the resolved velocities obtained by using Large-Eddy simulations at different mesh resolutions are compared with Direct Numerical Simulations data. The effectiveness of modeling the wall stresses by using local log-law is then tested on a relatively coarse grid. The results exhibit a good agreement between highly-resolved Large Eddy Simulations and Direct Numerical Simulations data regardless the Sub Grid Scale models. However, the agreement is less satisfactory with relatively coarse grid without using any wall models and the differences between Sub Grid Scale models are distinguishable. Using local wall model returned the basic flow topology and reduced significantly the differences between the coarse meshed Large-Eddy Simulations and Direct Numerical Simulations data. The results show that the ability of local wall model to predict the separation zone depends strongly on its implementation way.
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| 10. |
- Al Sam, Ali, et al.
(författare)
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The effect of moving waves on neutral marine atmospheric boundary layer
- 2014
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Ingår i: First Symposium on OpenFOAM® in Wind Energy. - : EDP Sciences. ; 2:01003
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Konferensbidrag (refereegranskat)abstract
- Large eddy simulations are performed to study the effects of wind-wave direction misalignment of the neutral marine atmospheric boundary layer over a wavy wall. The results show that the wind-wave misalignment has a significant effect on the velocity profiles and the pressure fluctuation over the wave surface. These effects are not confined to the near wave surface region but extend over the whole atmospheric surface layer.
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