We provide a detailed analysis of the shock formation process for the non-isentropic 2d Euler equations in azimuthal symmetry. We prove that from an open set of smooth and generic initial data, solutions of the Euler equations form a first singularity or gradient blow-up. This first singularity is termed a Hölder $ C^{\frac{1}{3}} $ pre-shock, and our analysis provides the first detailed description of this cusp solution. The novelty of this work relative to [
Citation: Isaac Neal, Steve Shkoller, Vlad Vicol. A characteristics approach to shock formation in 2D Euler with azimuthal symmetry and entropy[J]. Communications in Analysis and Mechanics, 2025, 17(1): 188-236. doi: 10.3934/cam.2025009
We provide a detailed analysis of the shock formation process for the non-isentropic 2d Euler equations in azimuthal symmetry. We prove that from an open set of smooth and generic initial data, solutions of the Euler equations form a first singularity or gradient blow-up. This first singularity is termed a Hölder $ C^{\frac{1}{3}} $ pre-shock, and our analysis provides the first detailed description of this cusp solution. The novelty of this work relative to [
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