2025
Modelling and mechanism of non-standard Richtmyer-Meshkov instability
Jiaxuan Li, Zhigang Zhai
Major Revision.
This study presents an analytical advancement in predicting perturbation amplitude growth rates for non-standard Richtmyer-Meshkov instability (RMI) induced by rippled shock waves interacting with heavy-light interfaces. We extend the irrotational model to encompass non-standard RMI scenarios, establishing a generalized framework validated through numerical simulations. Distinct from previous models, our model is free of empirical coefficients, and demonstrates superior accuracy across diverse perturbation configurations and Mach numbers. The analyses reveal the fundamental disparity of non-standard RMI from classical RMI: the vorticity deposition mechanism in non-standard RMI arises not only from normal pressure gradients at the shock front but crucially from tangential pressure gradients behind the shock wave. The asymptotic circulations are also well predicted by our model. Moreover, the relationship of the amplitudes between sinusoidal shock and perturbed interface is derived based on the model to realize the freeze-out of interface amplitude. The initial fundamental mode's amplitude growth is frozen well, and the mixing width is greatly suppressed.
Modelling and mechanism of non-standard Richtmyer-Meshkov instability
Jiaxuan Li, Zhigang Zhai
Major Revision.
This study presents an analytical advancement in predicting perturbation amplitude growth rates for non-standard Richtmyer-Meshkov instability (RMI) induced by rippled shock waves interacting with heavy-light interfaces. We extend the irrotational model to encompass non-standard RMI scenarios, establishing a generalized framework validated through numerical simulations. Distinct from previous models, our model is free of empirical coefficients, and demonstrates superior accuracy across diverse perturbation configurations and Mach numbers. The analyses reveal the fundamental disparity of non-standard RMI from classical RMI: the vorticity deposition mechanism in non-standard RMI arises not only from normal pressure gradients at the shock front but crucially from tangential pressure gradients behind the shock wave. The asymptotic circulations are also well predicted by our model. Moreover, the relationship of the amplitudes between sinusoidal shock and perturbed interface is derived based on the model to realize the freeze-out of interface amplitude. The initial fundamental mode's amplitude growth is frozen well, and the mixing width is greatly suppressed.
Atwood-number dependence of the Richtmyer–Meshkov instability at a heavy–light single-mode interface
Yinuo Xing, Chenren Chen, Jiaxuan Li, He Wang, Zhigang Zhai, Xisheng Luo
J. Fluid Mech. 2025
The dependence of the Richtmyer–Meshkov instability (RMI) on post-shock Atwood number ($|A_1|$) is experimentally investigated for a heavy–light single-mode interface. We create initial interfaces with density ratios of heavy to light gases ranging from 1.73 to 34.07, and achieve the highest $|A_1|$ value reported to date for gaseous-interface experiments (0.95).
Atwood-number dependence of the Richtmyer–Meshkov instability at a heavy–light single-mode interface
Yinuo Xing, Chenren Chen, Jiaxuan Li, He Wang, Zhigang Zhai, Xisheng Luo
J. Fluid Mech. 2025
The dependence of the Richtmyer–Meshkov instability (RMI) on post-shock Atwood number ($|A_1|$) is experimentally investigated for a heavy–light single-mode interface. We create initial interfaces with density ratios of heavy to light gases ranging from 1.73 to 34.07, and achieve the highest $|A_1|$ value reported to date for gaseous-interface experiments (0.95).
Attenuation of Richtmyer-Meshkov instability growth of fluid layer via double shock
Chenren Chen, Jiaxuan Li, Zhigang Zhai, Xisheng Luo
Sci. China-Phys. Mech. Astron. 2025
Suppression of the hydrodynamic instabilities involved in the inertial confinement fusion has attracted much attention but remains a challenge. In this work, we report the first theoretical analysis and experimental validation on attenuating the instability growth of a shock-accelerated fluid layer through a second shock impact.
Attenuation of Richtmyer-Meshkov instability growth of fluid layer via double shock
Chenren Chen, Jiaxuan Li, Zhigang Zhai, Xisheng Luo
Sci. China-Phys. Mech. Astron. 2025
Suppression of the hydrodynamic instabilities involved in the inertial confinement fusion has attracted much attention but remains a challenge. In this work, we report the first theoretical analysis and experimental validation on attenuating the instability growth of a shock-accelerated fluid layer through a second shock impact.
Manipulation of Richtmyer–Meshkov instability on a heavy–light interface via successive shocks
Zhigang Zhai, Chenren Chen, Yinuo Xing, Jiaxuan Li, Qing Cao, He Wang, Xisheng Luo
J. Fluid Mech. 2025
The manipulation of the Richtmyer–Meshkov instability growth at a heavy–light interface via successive shocks is theoretically analysed and experimentally realized in a specific shock-tube facility.
Manipulation of Richtmyer–Meshkov instability on a heavy–light interface via successive shocks
Zhigang Zhai, Chenren Chen, Yinuo Xing, Jiaxuan Li, Qing Cao, He Wang, Xisheng Luo
J. Fluid Mech. 2025
The manipulation of the Richtmyer–Meshkov instability growth at a heavy–light interface via successive shocks is theoretically analysed and experimentally realized in a specific shock-tube facility.
2024
Asymptotic matching modal model on Richtmyer–Meshkov instability
Jiaxuan Li, Chenren Chen, Zhigang Zhai, Xisheng Luo
J. Fluid Mech. 2025
An asymptotic matching modal model is established based on the singular perturbation method for predicting mode evolution in single- and dual-mode interfaces accelerated by a shock wave. The startup process is incorporated into the model to provide a complete description of the mode evolution after the shock impact. Through considering the feedback from high-order harmonic to the third-order harmonic, the model accuracy is improved and the model divergence is prevented. In addition, the model can evaluate the mutual-coupling effect on the amplitude variations of high-order harmonics besides the ‘beat modes’. To validate the model, experiments on both light–heavy and heavy–light interfaces subject to a shock wave are conducted, and both single- and dual-mode interfaces formed by the soap-film technique are involved. The interface profiles extracted from mode decomposition and predicted by the model show high consistency with the experimental counterparts. Good agreement of the mode amplitude growths between the experiments and theoretical predictions shows the superiority of the model, especially for the heavy–light interface.
Asymptotic matching modal model on Richtmyer–Meshkov instability
Jiaxuan Li, Chenren Chen, Zhigang Zhai, Xisheng Luo
J. Fluid Mech. 2025
An asymptotic matching modal model is established based on the singular perturbation method for predicting mode evolution in single- and dual-mode interfaces accelerated by a shock wave. The startup process is incorporated into the model to provide a complete description of the mode evolution after the shock impact. Through considering the feedback from high-order harmonic to the third-order harmonic, the model accuracy is improved and the model divergence is prevented. In addition, the model can evaluate the mutual-coupling effect on the amplitude variations of high-order harmonics besides the ‘beat modes’. To validate the model, experiments on both light–heavy and heavy–light interfaces subject to a shock wave are conducted, and both single- and dual-mode interfaces formed by the soap-film technique are involved. The interface profiles extracted from mode decomposition and predicted by the model show high consistency with the experimental counterparts. Good agreement of the mode amplitude growths between the experiments and theoretical predictions shows the superiority of the model, especially for the heavy–light interface.
Coupled Richtmyer–Meshkov and Kelvin–Helmholtz instability on a shock-accelerated inclined single-mode interface
Qing Cao, Jiaxuan Li, He Wang, Zhigang Zhai, Xisheng Luo
J. Fluid Mech. 2024
The coupling of Richtmyer–Meshkov instability (RMI) and Kelvin–Helmholtz instability (KHI), referred to as RM-KHI, on a shock-accelerated inclined single-mode air–SF$_6$ interface is studied through shock-tube experiments, focusing on the evolution of the perturbation distributed along the inclined interface.
Coupled Richtmyer–Meshkov and Kelvin–Helmholtz instability on a shock-accelerated inclined single-mode interface
Qing Cao, Jiaxuan Li, He Wang, Zhigang Zhai, Xisheng Luo
J. Fluid Mech. 2024
The coupling of Richtmyer–Meshkov instability (RMI) and Kelvin–Helmholtz instability (KHI), referred to as RM-KHI, on a shock-accelerated inclined single-mode air–SF$_6$ interface is studied through shock-tube experiments, focusing on the evolution of the perturbation distributed along the inclined interface.
Effects of disturbed transmitted shock and interface coupling on heavy gas layer evolution
Chenren Chen, Jiaxuan Li, Zhigang Zhai, Xisheng Luo
Phys. Fluids 2024
Development of a heavy gas layer with an upstream single-mode interface and a downstream planar interface accelerated by a shock wave is investigated. By considering the amplitude variation of the transmitted shock and interface coupling, a modified model is established, which provides good predictions on the linear growth rates of the perturbations on both interfaces.
Effects of disturbed transmitted shock and interface coupling on heavy gas layer evolution
Chenren Chen, Jiaxuan Li, Zhigang Zhai, Xisheng Luo
Phys. Fluids 2024
Development of a heavy gas layer with an upstream single-mode interface and a downstream planar interface accelerated by a shock wave is investigated. By considering the amplitude variation of the transmitted shock and interface coupling, a modified model is established, which provides good predictions on the linear growth rates of the perturbations on both interfaces.
Effects of compressibility on Richtmyer–Meshkov instability of heavy/light interface
Jiaxuan Li, Chenren Chen, Zhigang Zhai, Xisheng Luo
Phys. Fluids 2024
Experimental and numerical studies on the evolution of shock-accelerated SF$_6$/air interface with small initial amplitude are conducted. The effect of compressibility on the early development of perturbation is highlighted by varying shock intensity and fluid properties. The startup process is analyzed when rarefaction waves are reflected and the characteristic time of the startup process is provided. The relationship between the phase inversion process and the startup process under different incident shock strengths is clarified. According to the startup time, a new start point for normalization is given, which can better normalize the amplitude growth at the early stage. In addition, the effects of incident shock strength and physical properties of fluids on the linear growth rate are highlighted through numerical simulations. The incompressible linear model loses validity when the incident shock is strong, and the existing rotational model is verified to provide excellent predictions under any shock strengths. The decrease in adiabatic exponent of the heavy fluid or the increase in adiabatic exponent of the light fluid can reduce the linear growth rate. As the absolute value of Atwood number increases, the adiabatic exponent of the heavy fluid has a more significant effect on the linear growth than that of the light fluid..
Effects of compressibility on Richtmyer–Meshkov instability of heavy/light interface
Jiaxuan Li, Chenren Chen, Zhigang Zhai, Xisheng Luo
Phys. Fluids 2024
Experimental and numerical studies on the evolution of shock-accelerated SF$_6$/air interface with small initial amplitude are conducted. The effect of compressibility on the early development of perturbation is highlighted by varying shock intensity and fluid properties. The startup process is analyzed when rarefaction waves are reflected and the characteristic time of the startup process is provided. The relationship between the phase inversion process and the startup process under different incident shock strengths is clarified. According to the startup time, a new start point for normalization is given, which can better normalize the amplitude growth at the early stage. In addition, the effects of incident shock strength and physical properties of fluids on the linear growth rate are highlighted through numerical simulations. The incompressible linear model loses validity when the incident shock is strong, and the existing rotational model is verified to provide excellent predictions under any shock strengths. The decrease in adiabatic exponent of the heavy fluid or the increase in adiabatic exponent of the light fluid can reduce the linear growth rate. As the absolute value of Atwood number increases, the adiabatic exponent of the heavy fluid has a more significant effect on the linear growth than that of the light fluid..
2023
Richtmyer–Meshkov instability of a single-mode heavy–light interface in cylindrical geometry
Jiaxuan Li, He Wang, Zhigang Zhai, Xisheng Luo
Phys. Fluids 2023
Richtmyer–Meshkov (RM) instability of a single-mode SF$_6$–air interface subjected to a convergent shock is investigated experimentally. The convergent shock tube is specially designed with an opening tail to weaken the Rayleigh–Taylor effect and eliminate the reflected waves' effect. The gas layer scheme is used to create a heavy gas environment at the upstream side of the interface. Before phase inversion is finished, the amplitude reduction is accelerated, but the Bell–Plesset (BP) effect in this process is found to be negligible. After phase inversion is completed, the linear growth rate is generally predicted due to small amplitude and the weak BP effect. In nonlinear regime, an existing nonlinear model is revised based on the Padé approximation to give a better prediction of amplitude growth. The spike amplitude grows almost linearly, whereas the bubble amplitude gradually saturates and even reduces. For a heavy-light interface in convergent geometry, although both the spike and bubble amplitude growths are promoted by the BP effect, the spike growth is more promoted than the bubble. The BP effect enhances generation of the second-order harmonic, which results in saturation and reduction of the bubble amplitude. The discrepancy in the BP effect between light-heavy and heavy-light interfaces is qualitatively demonstrated for the first time.
Richtmyer–Meshkov instability of a single-mode heavy–light interface in cylindrical geometry
Jiaxuan Li, He Wang, Zhigang Zhai, Xisheng Luo
Phys. Fluids 2023
Richtmyer–Meshkov (RM) instability of a single-mode SF$_6$–air interface subjected to a convergent shock is investigated experimentally. The convergent shock tube is specially designed with an opening tail to weaken the Rayleigh–Taylor effect and eliminate the reflected waves' effect. The gas layer scheme is used to create a heavy gas environment at the upstream side of the interface. Before phase inversion is finished, the amplitude reduction is accelerated, but the Bell–Plesset (BP) effect in this process is found to be negligible. After phase inversion is completed, the linear growth rate is generally predicted due to small amplitude and the weak BP effect. In nonlinear regime, an existing nonlinear model is revised based on the Padé approximation to give a better prediction of amplitude growth. The spike amplitude grows almost linearly, whereas the bubble amplitude gradually saturates and even reduces. For a heavy-light interface in convergent geometry, although both the spike and bubble amplitude growths are promoted by the BP effect, the spike growth is more promoted than the bubble. The BP effect enhances generation of the second-order harmonic, which results in saturation and reduction of the bubble amplitude. The discrepancy in the BP effect between light-heavy and heavy-light interfaces is qualitatively demonstrated for the first time.
New interface formation method for shock–interface interaction studies
Jiaxuan Li, Qing Cao, He Wang, Zhigang Zhai, Xisheng Luo
Exp. Fluids 2023 My-Favorite-Work
We propose a new interface formation method for shock–interface interaction studies by using the super-hydrophobic–oleophobic surface instead of filaments to constrain the soap–film interface. To verify this method, developments of a single-mode air–SFinterface and a heavy gas layer accelerated by shock waves are experimentally investigated and compared with the previous studies. For single-mode interface developments, experimental schlieren images show that the interfaces are more fully developed, and the thickness of the interface profile reduces more than 60%. For shock-induced heavy gas layer instability, the interface profile is more distinct, and the mixing width of the upstream interface after it passes through the initial position of the downstream interface is largely weakened. Quantitative comparison shows that the filaments used to constrain the soap–film interface have a significant effect on the movement and amplitude growth of the upstream interface, and the superiority of the present method is well demonstrated.
New interface formation method for shock–interface interaction studies
Jiaxuan Li, Qing Cao, He Wang, Zhigang Zhai, Xisheng Luo
Exp. Fluids 2023 My-Favorite-Work
We propose a new interface formation method for shock–interface interaction studies by using the super-hydrophobic–oleophobic surface instead of filaments to constrain the soap–film interface. To verify this method, developments of a single-mode air–SFinterface and a heavy gas layer accelerated by shock waves are experimentally investigated and compared with the previous studies. For single-mode interface developments, experimental schlieren images show that the interfaces are more fully developed, and the thickness of the interface profile reduces more than 60%. For shock-induced heavy gas layer instability, the interface profile is more distinct, and the mixing width of the upstream interface after it passes through the initial position of the downstream interface is largely weakened. Quantitative comparison shows that the filaments used to constrain the soap–film interface have a significant effect on the movement and amplitude growth of the upstream interface, and the superiority of the present method is well demonstrated.