A multiscale technique for the validation of a numerical code for predicting the pressure field induced by a high-power spark

Villa, Andrea; Malgesini, Roberto; Barbieri, Luca

doi:10.1088/0022-3727/44/16/165201

Cited by 9 publications

(14 citation statements)

References 54 publications

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“…We can use these results to validate the current approach, and henceforth these two models shall be referred to as M16 and VMB11 respectively. [11]. A plasma arc is generated between an electrode and a metal plate.…”

Section: Validationmentioning

confidence: 99%

Multi-physics simulations of lightning strike on elastoplastic substrates

Millmore

Nikiforakis

2020

Journal of Computational Physics

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This work is concerned with the numerical simulation of elastoplastic, electromagnetic and thermal response of aerospace materials due to their interaction with a plasma arc under lightning strike conditions. Current approaches treat the interaction between these two states of matter either in a decoupled manner or through one-way coupled 'cosimulation'. In this paper a methodology for multiphysics simulations of two-way interaction between lightning and elastoplastic materials is presented, which can inherently capture the non-linear feedback between these two states of matter. This is achieved by simultaneously solving the magnetohydrodynamic and the elastoplastic systems of equations on the same computational mesh, evolving the magnetic and electric fields dynamically. The resulting model allows for the topological evolution and movement of the arc attachment point coupled to the structural response and Joule heating of the substrate. The dynamic communication between the elastoplastic material and the plasma is facilitated by means of Riemann problem-based ghost fluid methods. This two-way coupling, to the best of the authors' knowledge, has not been previously demonstrated. The proposed model is first validated against experimental laboratory studies, demonstrating that the growth of the plasma arc can be accurately reproduced, dependent on the electrical conductivity of the substrate. It is then subsequently evaluated in a setting where the dynamically-evolved properties within the substrate feed back into the plasma arc attachment. Results are presented for multi-layered substrates of different materials, and for a substrate with temperature-dependent electrical conductivity. It is demonstrated that these conditions generate distinct behaviour due to the interaction between the plasma arc and the substrate.

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Section: Validationmentioning

confidence: 99%

Multi-physics simulations of lightning strike on elastoplastic substrates

Millmore

Nikiforakis

2020

Journal of Computational Physics

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“…In order to compare the different radiative models, an initial assessment was made using a one-dimensional, cylindrical plasma arc. This follows experimental and numerical studies of Villa et al 26 , and was used to validate the underlying numerical framework by Millmore and Nikiforakis 27 . Experimentally, a plasma arc attaches to a highly conductive metal substrate within an set up large enough such that the arc can be treated as cylindrical.…”

Section: Numerical Resultsmentioning

confidence: 97%

“…The grey body model is of simplified NEC model used by Villa et al 26 . Although this approach simplifies the underlying model for solving the RTE, by neglecting spectral and geometric dependencies, it does add complexity in the techniques for solving equation (6); this process can be broken down into three steps.…”

Section: B Grey Body Modelmentioning

confidence: 99%

“…Within this work, four spectral methods are considered, with their formulation for use in one-dimensional lightning arc simulations evaluated. The NEC, P 1 and SP 3 are considered, along with an alternative NEC approach considered by Villa et al 26 . This latter approach treats the plasma as a grey body of constant emissivity and solves a simplified RTE using the temperature, density and at specific heat capacity of the plasma at a given point.…”

Section: Introductionmentioning

confidence: 99%

“…TABLE I: Initial conditions for a cylindrical plasma arc, reproducing the experiment of Villa et al 26 .…”

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confidence: 99%

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Equation of state driven radiative models for simulation of lightning strikes

Apsley,

Millmore,

Nikiforakis

2021

Preprint

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This work is concerned with the numerical simulation of plasma arc interaction with aerospace substrates under conditions akin to lightning strike and in particular with the accurate calculation of radiative heat losses. These are important because they have a direct effect on the calculation of thermal and pressure loads on the substrates, which can lead to material damage under certain conditions. Direct numerical solution of the radiation transport equation (RTE) in mesoscale simulations is not viable due to its computational cost, so for practical applications reduced models are usually employed. To this end, four approximations for solving the RTE are considered in this work, ranging from a simple local thermodynamical behaviour consideration, to a more complex spectral absorption dependent on the arc geometry. Their performance is initially tested on a one-dimensional cylindrical arc, before implementing them in a multi-dimensional magnetohydrodynamics code. Results indicate that inclusion of spectral absorption is necessary in order to obtain consistent results. However, the approaches accounting for the arc geometry require repeated solution of the computationally intensive Helmholtz equations, making them prohibitive for multi-dimensional simulations. As an alternative, a method using the net emission coefficient is employed, which provides a balance between computational efficiency and accuracy, as shown by comparisons against experimental measurements for a plasma arc attaching to an aluminium substrate.

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