ALE vs. ICFD
zhou zhou
Hi Dear all,
I noticed, in LS-DYNA, there are two options for the fluid modeling, with one as arbitrary Lagrangian-Eulerian method and the other as incompressible computational fluid dynamics. What was the pros and cons of these two approaches, respectively? It will be very interesting to read if there are papers comparing these two approaches.
Any discussion/comments are highly appreciated.
Best,
Zhou
James M. Kennedy
Dear Zhou,
LS-DYNA wave-structure interaction simulations using ALE (standard), S-ALE, ICFD, and SPH models.
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ALE (standard) - Intermediate example presentation
https://www.dynaexamples.com/ale/intermediate-example
Intermediate : Wave-Structure Interaction
A container is partially filled with water subjected to gravity. As the wave propagates, it hits a rigid column placed roughly in the middle of the container. This model was developed to make/allow comparisons with an available S-ALE model. To make a direct comparison, using identical cell discretization (0.010 meters) one can modify the S-ALE model (wavehitcol.k) below by making a simple parameter change (node numbering) in the three *ALE_STRUCTURED_MESH_CONTROL_POINTS keyword entries.
Roughly 330,000 elements are in the ALE and S-ALE models with a cell discretization of 0.010 meters (m), while roughly 2,590,000 elements are in the S-ALE model (wavehitcol.k) with a cell discretization of 0.005 meters (m).
The Murnaghan equation of state has become available as a new keyword: *EOS_MURNAGHAN. This equation of state can be used to enforce quasi-static incompressibility while allowing for a reasonable time step in explicit calculations. Any ALE model part is therefore represented by a *MAT_NULL card, describing the density and viscosity of the material, and an *EOS_MURNAGHAN card, describing the pressure-density relationship.
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S-ALE - Intermediate example presentation
http://ftp.lstc.com/anonymous/outgoing/hao/sale/models/wavehitcol/
Intermediate : Wave-Structure Interaction
A container is partially filled with water subjected to gravity. As the wave propagates, it hits a rigid column placed roughly in the middle of the container. The total contact forces are recorded for the entire simulation, and compared to experimental data [1].
[1} Gomez-Gesteira, M., Crespo, A.J.C., Rogers, B.D. Dalrymple, R.A., Dominguez, J.M. and Barreiro, A., “SPHysics - Development of a Free-Surface Fluid Solver - Part 2: Efficiency and Test Cases,” Computers & Geosciences, Vol. 48, pp. 300–307, November, 2012.
https://www.sciencedirect.com/science/article/pii/S0098300412000842
[2] Chen, H., "LS-DYNA Structured ALE (S-ALE) Solver", 14th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2016.
[3] Chen, H, and Do, I., "Recent Developments in LS-DYNA S-ALE", 15th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2018.
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ICFD - Intermediate example presentation
https://www.dynaexamples.com/icfd/intermediate-examples/dam3
Intermediate : Water Impact on Rigid Column
This case simulates the impact of a water column on a rigid obstacle and compares results with the experiment [1].
[1} Gomez-Gesteira, M., Crespo, A.J.C., Rogers, B.D. Dalrymple, R.A., Dominguez, J.M. and Barreiro, A., “SPHysics - Development of a Free-Surface Fluid Solver - Part 2: Efficiency and Test Cases,” Computers & Geosciences, Vol. 48, pp. 300–307, November, 2012.
https://www.sciencedirect.com/science/article/pii/S0098300412000842
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SPH - Intermediate example presentation
https://www.dynaexamples.com/sph/intermediate-examples/wavestructure
Intermediate : Wave-Structure Interaction
A container is partially filled with water subjected to gravity. As the wave propagates, it hits a rigid column placed roughly in the middle of the container. The total contact forces are recorded for the entire simulation, and compared to experimental data [1].
[1} Gomez-Gesteira, M., Crespo, A.J.C., Rogers, B.D. Dalrymple, R.A., Dominguez, J.M. and Barreiro, A., “SPHysics - Development of a Free-Surface Fluid Solver - Part 2: Efficiency and Test Cases,” Computers & Geosciences, Vol. 48, pp. 300–307, November, 2012.
https://www.sciencedirect.com/science/article/pii/S0098300412000842
[2] Yreux, E., "Fluid Flow Modeling with SPH in LS-DYNA", 15th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2018.
The Murnaghan equation of state has become available as a new keyword: *EOS_MURNAGHAN. This equation of state can be used to enforce quasi-static incompressibility while allowing for a reasonable time step in explicit calculations. Any SPH model part is therefore represented by a *MAT_NULL card, describing the density and viscosity of the material, and an *EOS_MURNAGHAN card, describing the pressure-density relationship.
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Sincerely,
James M. Kennedy
KBS2 Inc.
November 25, 2021
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Ameen Topa
[1] Cai, Zhemin, Ameen Topa, Luke P. Djukic, Manudha T. Herath, and Garth MK Pearce. "Evaluation of rigid body force in liquid sloshing problems of a partially filled tank: Traditional CFD/SPH/ALE comparative study." Ocean Engineering 236 (2021): 109556. .
Ameen
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