The hydrodynamic instability research in fluid mechanics establishes whether a flow is stable or unstable, and if so, how these instabilities produce turbulent mixing. The Richtmyer–Meshkov (RM) instability is a shock-driven hydrodynamic instability that occurs in a combination with the Kelvin-Helmholtz instability when an initially perturbed surface separating by distinct fluid properties is driven by an incident shock wave. The RM instability can be considered as the impulsive limit of Rayleigh-Taylor instability where primary perturbations expand across the surface and ultimately emerge into a turbulent fluid mixing as the uniform gravitational acceleration increases. The studies on development of shock-induced instability are essential for the investigation of difficult issues related to shock propagation through arbitrarily inhomogeneous materials because of its wide range of applications, such as inertial confinement fusion, supersonic combustion, and supernova explosions.
In this talk, high-fidelity simulations on the development of shock-induced hydrodynamic instabilities for light/heavy bubbles of various shapes are presented. The focus is placed on presenting more intuitive details of the flow-fields visualizations, wave patterns, bubble deformation, vorticity production, and enstrophy evolution. For these simulations, two-dimensional compressible Euler/Navier-Fourier equations are simulated with a high-order mixed-type modal discontinuous Galerkin method. Additionally, a thorough investigation is made into the impact of shock strength, Atwood number, aspect ratios, and bulk viscosity in diatomic and polyatomic gases on the flow morphologies of shock-induced hydrodynamic instabilities.
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