Numerical modeling of high aspect ratio flexible fibers in inertial flows

Kunhappan, Deepak; Harthong, Barthélémy; Chareyre, Bruno; Balarac, Guillaume; Dumont, Pierre

doi:10.1063/1.5001514

Cited by 26 publications

(10 citation statements)

References 46 publications

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“…Two-way coupling using a field of body forces was presented by Lindström and Uesaka [23,24] to conserve momentum in the direct bundle simulation. However, they utilize the drag of prolate spheroids, which leads to a total drag force on a fiber that depends on discretization [25]. Direct models have been utilized in representative volume elements to determine rheological properties [26,27], contact properties in microstructures [28] and parameters of macroscopic fiber orientation models [21].…”

Section: Introductionmentioning

confidence: 99%

Direct Bundle Simulation approach for the compression molding process of Sheet Molding Compound

Meyer

Schöttl

Bretz

et al. 2020

Composites Part A: Applied Science and Manufacturing

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The manufacturing process of Sheet Molding Compounds (SMC) induces a reorientation of fibers during the flow, which influences local properties and is of interest for structural computations. Typically, the reorientation is described with an evolution equation for the second order fiber orientation tensor, which requires a closure approximation and multiple empirical parameters to describe long fibers. However, CT scans of SMC microstructures show that fiber bundles stay mostly intact during molding. Treating hundreds of fibers in such a bundle as one instance enables direct simulation on component scale. This work proposes a direct simulation approach, in which bundle segments experience Stokes' drag forces and opposing forces are applied to the fluid field. The method is applied to specimens with a double-curved geometry and compared to CT scans. The Direct Bundle Simulation provides increased accuracy of fiber orientations and enables prediction of fiber-matrix separation with affordable computational effort at component scale.

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Section: Introductionmentioning

confidence: 99%

Direct Bundle Simulation approach for the compression molding process of Sheet Molding Compound

Meyer

Schöttl

Bretz

et al. 2020

Composites Part A: Applied Science and Manufacturing

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show abstract

“…The questions which have been addressed are the orientation dynamics and preferential orientation of non-spherical objects in homogeneous [5] or wall-bounded turbulence [6]. Compared to the very large number of references related to particle suspensions, lower attention has been paid to the more complicated systems of flexible fibers in a turbulent fluid [7]. Polymer physics is a vast field of research on flexible filament dynamics.…”

Section: Literature Overviewmentioning

confidence: 99%

Numerical modelling of long flexible fibers in homogeneous isotropic turbulence

et al. 2019

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We numerically investigated the transport, deformation and buckling events of an isolated elastic fiber in Taylor-Green vortices and studied the dynamics of long filaments in homogeneous isotropic turbulence. The fiber is modelled by an assembly of spherical beads. The contact between beads enforces the inextensibility of the filament while bending is accounted for by the Gears Bead Model (GBM) proposed by Delmotte et al. (2015). In the cellular Taylor-Green flow, the buckling probability is a function of a dimensionless number, called Sperm number, which is a balance between the compression rate of the flow and the elastic response of the filament. The shapes of the filament and its ability to buckle have been successfully validated through comparisons with experiments from the work by Quennouz et al. (2015). The deformation statistics of long flexible fibers in sustained homogeneous isotropic turbulence were analyzed for various flow and fiber material conditions. Two regimes have been identified depending on the ratio of fiber length to persistence length which is a measure of turbulent forcing to flexibility. The numerical results are in good agreement with existing experimental data (C. Brouzet et al., Phys. Rev. Lett. 112, 074501 (2014)) validating the assumptions of our model for the configurations we investigated.

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“…A full description of the bonded‐sphere fiber model is provided in Guo et al, 2 in which a criterion to determine the critical time step for the numerical stability based on the bond properties was proposed. Effeindzourou et al 3 and Kunhappan et al 4 proposed a general scheme for the modeling of deformable structures, which is applicable in the simulation of flexible fibers. In their work, a fiber is treated as a chain of sphero‐cylinders 4 .…”

Section: Introductionmentioning

confidence: 99%

“…Effeindzourou et al 3 and Kunhappan et al 4 proposed a general scheme for the modeling of deformable structures, which is applicable in the simulation of flexible fibers. In their work, a fiber is treated as a chain of sphero‐cylinders 4 . In the prolate spheroid‐chain model and the cylindrical rod‐chain model by Lindstrom and Uesaka 5 and Wu and Aidun, 6 the axial extension/compression is ignored, and the connectivity of two segments in a fiber chain is ensured by imposing the “no‐slip” condition that the relative velocity between them at the joint is zero.…”

Section: Introductionmentioning

confidence: 99%

“…Three contact types exist between two sphero‐cylinders: hemisphere–hemisphere contact, hemisphere–cylinder contact, and cylinder–cylinder contact. In previous flexible fiber simulations, 3‐5 the same contact force model was used for different contact types. However, different contact types lead to different geometries of the contact zone, inevitably causing differences in contact forces.…”

Section: Introductionmentioning

confidence: 99%

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Discrete element method models of elastic and elastoplastic fiber assemblies

Guo

Liu

et al. 2021

AIChE Journal

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Geometry‐dependency and plasticity are considered in the contact force models for the discrete element method simulations of elastic and elastoplastic fiber assemblies subject to uniaxial compression. It is observed that the contact force models have a significant impact on compressive loads. A simplified normal contact force model leads to smaller loads at large solid volume fractions compared to the experimental results, while the present geometry‐dependent models give better predictions. Simulations with a simple Coulombic tangential contact force model (considering sliding friction only) significantly underestimate the loads, while a Mindlin tangential force model that considers static friction improves the predictions. For the modeling of the fibers that undergo large plastic deformations, plasticity should be considered for both the fiber bending and fiber–fiber normal contact in order to obtain correct simulation results. Elastic models for fiber–fiber contact and fiber bending deformation remarkably overpredict the loads for the plastic fibers.

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Numerical modeling of high aspect ratio flexible fibers in inertial flows

Abstract: International audienc

Cited by 26 publications

References 46 publications

Direct Bundle Simulation approach for the compression molding process of Sheet Molding Compound

Direct Bundle Simulation approach for the compression molding process of Sheet Molding Compound

Numerical modelling of long flexible fibers in homogeneous isotropic turbulence

Discrete element method models of elastic and elastoplastic fiber assemblies

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