Constrained optimization framework for interface-aware sub-scale dynamics models for voids closure in Lagrangian hydrodynamics

Barlow, Andrew; Klima, Matej; Shashkov, Mikhail

doi:10.1016/j.jcp.2018.03.034

Cited by 12 publications

(4 citation statements)

References 12 publications

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“…Other methods with which this work can be compared and contrasted include Klima et al [35] and Barlow et al [3] The void generation flux-modifier is applied in all interfacial cells that are coming apart. Material interfaces are flagged in the same way as the shear flux-modifier, namely when a volume fraction 'changes sign' between the two cells.…”

Section: Voidmentioning

confidence: 99%

A flux-enriched Godunov method for multi-material problems with interface slide and void opening

Wallis

Barton

Nikiforakis

2021

Journal of Computational Physics

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Section: Voidmentioning

confidence: 99%

A flux-enriched Godunov method for multi-material problems with interface slide and void opening

Wallis

Barton

Nikiforakis

2021

Journal of Computational Physics

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“…Considering the mesh movements explicitly in the differential equations, direct ALE method has to solve the advection terms of the fluid equations in the form of ALE, the high-order direct ALE scheme can be developed more easily [19], but it is difficult in updating nonlinear physical variables which depend on the history such as stresses and strains. The indirect ALE method is called also as three-stage ALE or split ALE, which is comprised of three stages: (1) Lagrangian stage, in which the solution is updated, and nodes move in Lagrangian style; (2) Rezoning stage, in which the nodes of Lagrangian mesh move to more optimal positions to improve the quality of the mesh; (3) Remapping stage, in which the Lagrangian solution on the Lagrangian mesh is remapped onto the rezoned mesh. Because of the splitting operation, the indirect ALE method is more compatible with the Lagrangian method, and it is complemented more easily based on the existed Lagrangian codes, therefore it is extensively employed in production codes.…”

Section: Introductionmentioning

confidence: 99%

“…For multi-material cells, the closure model must be demanded to distribute the change in total volume of the multi-material cell between material components, update internal energy of each material component and common pressure of multi-material cells. The closure model has been an open problem until now [3,25], and is still developing to obtain the more physical models recently [1,2]. The challenge of the closure model is to define the state of mixtures despite the lack of information about the velocity distribution within multi-material cells.…”

Section: Introductionmentioning

confidence: 99%

A 2D Staggered Multi-Material ALE Code Using MOF Interface Reconstruction

Chen¹

2021

NMTMA

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Hydrocodes are necessary numerical tools in the fields of implosion and high-velocity impact, which often involve large deformations with changing-topology interfaces. It is very difficult for Lagrangian or Simplified Arbitrary Lagrangian-Eulerian (SALE) codes to tackle these kinds of large-deformation problems, so a staggered Multi-Material ALE (MMALE) code is developed in this paper, which is the explicit time-marching Lagrange plus remap type. We use the Moment Of Fluid (MOF) method to reconstruct the interfaces of multi-material cells and present an adaptive bisection method to search for the global minimum value of the nonlinear objective function. To keep the Lagrangian computations as long as possible, we develop a robust rezoning method named as Combined Rezoning Method (CRM) to generate the convex, smooth grids for the large-deformation domain. Regarding the staggered remap phase, we use two methods to remap the variables of Lagrangian mesh to the rezoned one. One is the first-order intersection-based remapping method that doesn't limit the distances between the rezoned and Lagrangian meshes, so it can be used in the applications of wide scope. The other one is the conservative secondorder flux-based remapping method developed by Kucharika and Shashkov [22] that requires the rezoned element to locate in its adjacent old elements. Numerical results of triple point problem show that the result of first-order remapping method using ALE computations is gradually convergent to that of second-order remapping method using Eulerian computations with the decrease of rezoning, thereby telling us that MMALE computations should be performed as few as possible to reduce the errors of the interface reconstruction and the remapping. Numerical results provide a clear evidence of the robustness and the accuracy of this MMALE scheme, and that our MMALE code is powerful for the large-deformation problems.

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“…Moreover, these models developed at the end of the 20th century are the current state of the art to describe void dynamics [15,25,28]. Recently, a new model of void dynamics in multiphase flow, coupling multiple physics at different scales and using optimization algorithms for convergence was derived in [4]. However its application to a real composite material part would be complicated and cumbersome.…”

Section: Introductionmentioning

confidence: 99%

A non-local void dynamics modeling and simulation using the Proper Generalized Decomposition

et al. 2019

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In this work we develop a void filling and void motion dynamics model using volatile pressure and squeeze flow during tape placement process. The void motion and filling are simulated using a non-local model where their presence is reflected in the global macroscale behavior. Local pressure gradients during compression do play a critical role in void dynamics, and hence the need for a non-local model. Deriving a non-local model accounting for all the void motion and dynamics entails a prohibitive number of degrees of freedom, leading to unrealistic computation times with classical solution techniques. Hence, Proper Generalized Decomposition -PGD -is used to solve the aforementioned model. In fact, PGD circumvents the curse of dimensionality by using separated representation of the space coordinates. For example, a 2D problem can be solved as a sequence of 1D problems to find the 2D solution. The non-local model solution sheds light on the fundamental of the void dynamics including their pressure variation, motion and closure mechanisms. Finally, a post treatment of the transient compression of the voids is used to derive conclusions regarding the physics of the void dynamics.

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Constrained optimization framework for interface-aware sub-scale dynamics models for voids closure in Lagrangian hydrodynamics

Cited by 12 publications

References 12 publications

A flux-enriched Godunov method for multi-material problems with interface slide and void opening

A flux-enriched Godunov method for multi-material problems with interface slide and void opening

A 2D Staggered Multi-Material ALE Code Using MOF Interface Reconstruction

A non-local void dynamics modeling and simulation using the Proper Generalized Decomposition

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