Abstract:Shock-induced finite-thickness fluid layer evolution is investigated numerically and theoretically. Specifically, two-dimensional helium layers consisting of two interfaces owning diverse perturbation phases are considered to explore the interface-coupling on the Richtmyer–Meshkov instability (RMI). A general linear model is first established to quantify the phase effect on the RMI of the two interfaces of an arbitrary fluid layer. The linear model is validated with the present numerical results. As the phase … Show more
“…2019; Liang et al. 2020 b ; Liang 2022 b ). A comprehensive review of the scheme and its extensive applications was recently reported by Jiang, Wen & Zhang (2020).…”
Section: Experimental and Numerical Methodsmentioning
confidence: 99%
“…Open boundary conditions are enforced on the left and right boundaries ( and mm) to eliminate the waves reflected from the left and right boundaries (Liang et al. 2020 b ; Liang 2022 b ), and reflection conditions are imposed at the top and bottom boundaries ( and mm), respectively. Figure 2.Schematics of the initial simulation setup, where and represent the amplitudes of the upstream interface and downstream interface, respectively.…”
Section: Experimental and Numerical Methodsmentioning
confidence: 99%
“…The contact discontinuity restoring Harten-Lax-van Leer contact Riemann solver (Toro, Spruce & Speares 1994) is used to determine the numerical fluxes between the conservation elements. The use of this scheme in capturing shocks and details of complex flow structures for the RMI issues and shock-droplet interactions has been well validated Guan et al 2018;Fan et al 2019;Liang et al 2020b;Liang 2022b). A comprehensive review of the scheme and its extensive applications was recently reported by Jiang, Wen & Zhang (2020).…”
Shock-induced instability developments of two successive interfaces have attracted much attention, but remain a difficult problem to solve. The feedthrough and reverberating waves between two successive interfaces significantly influence the hydrodynamic instabilities of the two interfaces. The evolutions of two successive slow/fast interfaces driven by a weak shock wave are examined experimentally and numerically. First, a general one-dimensional theory is established to describe the movements of the two interfaces by studying the rarefaction waves reflected between the two interfaces. Second, an analytical, linear model is established by considering the arbitrary wavenumber and phase combinations and compressibility to quantify the feedthrough effect on the Richtmyer–Meshkov instability (RMI) of two successive slow/fast interfaces. The feedthrough significantly influences the RMI of the two interfaces, and even leads to abnormal RMI (i.e. phase reversal of a shocked slow/fast interface is inhibited) which is the first observational evidence of the abnormal RMI provided by the present study. Moreover, the stretching effect and short-time Rayleigh–Taylor instability or Rayleigh–Taylor stabilisation imposed by the rarefaction waves on the two interfaces are quantified considering the two interfaces’ phase reversal. The conditions and outcomes of the freeze-out and abnormal RMI caused by the feedthrough are summarised based on the theoretical model and numerical simulation. A specific requirement for the simultaneously freeze-out of the instability of the two interfaces is proposed, which can potentially be used in the applications to suppress the hydrodynamic instabilities.
“…2019; Liang et al. 2020 b ; Liang 2022 b ). A comprehensive review of the scheme and its extensive applications was recently reported by Jiang, Wen & Zhang (2020).…”
Section: Experimental and Numerical Methodsmentioning
confidence: 99%
“…Open boundary conditions are enforced on the left and right boundaries ( and mm) to eliminate the waves reflected from the left and right boundaries (Liang et al. 2020 b ; Liang 2022 b ), and reflection conditions are imposed at the top and bottom boundaries ( and mm), respectively. Figure 2.Schematics of the initial simulation setup, where and represent the amplitudes of the upstream interface and downstream interface, respectively.…”
Section: Experimental and Numerical Methodsmentioning
confidence: 99%
“…The contact discontinuity restoring Harten-Lax-van Leer contact Riemann solver (Toro, Spruce & Speares 1994) is used to determine the numerical fluxes between the conservation elements. The use of this scheme in capturing shocks and details of complex flow structures for the RMI issues and shock-droplet interactions has been well validated Guan et al 2018;Fan et al 2019;Liang et al 2020b;Liang 2022b). A comprehensive review of the scheme and its extensive applications was recently reported by Jiang, Wen & Zhang (2020).…”
Shock-induced instability developments of two successive interfaces have attracted much attention, but remain a difficult problem to solve. The feedthrough and reverberating waves between two successive interfaces significantly influence the hydrodynamic instabilities of the two interfaces. The evolutions of two successive slow/fast interfaces driven by a weak shock wave are examined experimentally and numerically. First, a general one-dimensional theory is established to describe the movements of the two interfaces by studying the rarefaction waves reflected between the two interfaces. Second, an analytical, linear model is established by considering the arbitrary wavenumber and phase combinations and compressibility to quantify the feedthrough effect on the Richtmyer–Meshkov instability (RMI) of two successive slow/fast interfaces. The feedthrough significantly influences the RMI of the two interfaces, and even leads to abnormal RMI (i.e. phase reversal of a shocked slow/fast interface is inhibited) which is the first observational evidence of the abnormal RMI provided by the present study. Moreover, the stretching effect and short-time Rayleigh–Taylor instability or Rayleigh–Taylor stabilisation imposed by the rarefaction waves on the two interfaces are quantified considering the two interfaces’ phase reversal. The conditions and outcomes of the freeze-out and abnormal RMI caused by the feedthrough are summarised based on the theoretical model and numerical simulation. A specific requirement for the simultaneously freeze-out of the instability of the two interfaces is proposed, which can potentially be used in the applications to suppress the hydrodynamic instabilities.
“…As the research progresses, the problem being studied and the models being used are becoming more and more practical and complex [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. In recent years, the results in statistical physics perspectives obtained with the help of Discrete Boltzmann Method (DBM) and complex physical field analysis techniques have also provided a range of new insights into the study of hydrodynamic instabilities.…”
The Rayleigh-Taylor Instability (RTI) in compressible flow with inter-molecular interactions is probed via the Discrete Boltzmann Method (DBM). The effects of interfacial tension, viscosity and heat conduction are investigated. It is found that the influences of interfacial tension on the perturbation amplitude, bubble velocity, and two kinds of entropy production rates all show differences at different stages of RTI evolution. It inhibits the RTI evolution at the bubble acceleration stage, while at the asymptotic velocity stage, it first promotes and then inhibits the RTI evolution.Viscosity and heat conduction inhibit the RTI evolution. Viscosity shows a suppressive effect on entropy generation rate related to heat flow at the early stage but a first promotive and then suppressive effect on entropy generation rate related to heat flow at a later stage. Heat conduction shows a promotive effect on entropy generation rate related to heat flow at an early stage. Still, it offers a first promotive and then suppressive effect on entropy generation rate related to heat flow at a later stage. By introducing the morphological boundary length, we found that the stage of exponential growth of interface length with time corresponds to the bubble acceleration stage. The first maximum point of interface length change rate and the first maximum point of the change rate of entropy generation rate related to viscous stress can be used as a new criterion for RTI to enter the asymptotic velocity stage.
“…RMI has also been extensively studied [34][35][36][37] in theory [38][39][40][41][42] , numerical simulations [43][44][45][46][47][48][49][50][51][52][53][54][55][56] , and experiments [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72] for general conditions. The physical comprehension of RMI is becoming clearer, however, as for general fluid cases, there are also significant nonequilibrium kinetic effects and this part is missing for the majority of existing studies.…”
Nonequilibrium kinetic effects are widespread in fluid systems and might have a significant impact on the inertial confinement fusion ignition process, and the entropy production rate is a key factor in accessing the compression process. But relevant research is little due to the lack of convenient physical model. In this work, we study the Richtmyer-Meshkov instability (RMI) and the reshock process by a two-fluid discrete Boltzmann method (DBM). The work starts from interpreting the experiment by Collins and Jacobs [J. Fluid Mech. 464, 113-136 (2002)]. Firstly, the DBM result for the perturbation amplitude evolution is in good agreement with that of experiment. It is found that shock wave causes substances near the substance interface to deviate more significantly from their thermodynamic equilibrium state. Greatly different from the case of normal shocking on unperturbed plane interface between two uniform media, which is well described by the Rankine-Hugoniot relations and where all Thermodynamic Non-Equilibrium (TNE) quantities quickly recover to zero behind the shock front, in the RMI case, the TNE quantities show complex but inspiring kinetic effects in the shocking process and behind the shock front. The kinetic effects are detected by two sets of TNE quantities. The first set are |∆ * 2 |, ∆ * 3,1 , ∆ * 3 , and ∆ * 4,2 . They correspond to the intensities of the Non-Organized Momentum Flux(NOMF), Non-Organized Energy Flux(NOEF), flux of NOMF and flux of NOEF. All the four TNE measures abruptly increase in the shocking process. ∆ * 3,1 and ∆ * 3 have the same dimension and show similar behaviors. They continue to increase in a much lower rate behind the shock front. |∆ * 2 | and ∆ * 4,2 have different dimensions, but show similar behaviors. They quickly decrease to be very small behind the shock front. The second set of TNE quantities are ṠNOMF , ṠNOEF and Ṡsum . They are entropy production rates due to NOMF, NOEF and their summation. It is found that the mixing zone is the primary contribution region to the ṠNOEF , while the flow field region excluding mixing zone is the primary contribution region to the ṠNOMF . Each substance behaves differently in terms of entropy production rate, and the light fluid has a higher entropy production rate than the heavy fluid.
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