Spontaneous singularity formation in converging cylindrical shock waves
KAUST DepartmentFluid and Plasma Simulation Group (FPS)
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
KAUST Grant NumberURF/1/2162-01
Permanent link to this recordhttp://hdl.handle.net/10754/631521
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AbstractWe develop a nonlinear, Fourier-based analysis of the evolution of a perturbed, converging cylindrical strong shock using the approximate method of geometrical shock dynamics (GSD). This predicts that a singularity in the shock-shape geometry, corresponding to a change in Fourier-coefficient decay from exponential to algebraic, is guaranteed to form prior to the time of shock impact at the origin, for arbitrarily small, finite initial perturbation amplitude. Specifically for an azimuthally periodic Mach-number perturbation on an initially circular shock with integer mode number q and amplitude proportional to ϵ1, a singularity in the shock geometry forms at a mean shock radius Ru,c∼(q2ϵ)-1/b1, where b1(γ)<0 is a derived constant and γ the ratio of specific heats. This requires q2ϵ1, q≫1. The constant of proportionality is obtained as a function of γ and is independent of the initial shock Mach number M0. Singularity formation corresponds to the transition from a smooth perturbation to a faceted polygonal form. Results are qualitatively verified by a numerical GSD comparison.
CitationMostert W, Pullin DI, Samtaney R, Wheatley V (2018) Spontaneous singularity formation in converging cylindrical shock waves. Physical Review Fluids 3. Available: http://dx.doi.org/10.1103/PhysRevFluids.3.071401.
SponsorsThis research was supported by the KAUST Office of Sponsored Research under Award No. URF/1/2162-01.
PublisherAmerican Physical Society (APS)
JournalPhysical Review Fluids