High Mach number Kelvin-Helmholtz instability with DG and subcell positivity limiter

We solve the compressible Euler equations of gas dynamics with a fourth-order accurate entropy-stable discontinuous Galerkin (DG) method and combine it with a first-order accurate finite volume (FV) method at the node level to impose positivity of density and pressure [1,2].

The video shows the evolution of the density in time using 1024² degrees of freedom. We use the entropy-conservative and kinetic energy preserving flux of Ranocha [3] for the volume fluxes and the Rusanov solver for the surface fluxes of the DG and FV methods. During this simulation, the FV method acts on average in 0.000086% of the computational domain, and never more than 0.002% of the computational domain at a specific time.

References
[1] A. M. Rueda-Ramírez, G. J. Gassner, A Subcell Finite Volume Positivity-Preserving Limiter for DGSEM Discretizations of the Euler Equations, in: WCCM-ECCOMAS2020, pp. 1–12.
[2] A. M. Rueda-Ramírez, W. Pazner, G. J. Gassner, Subcell limiting strategies for discontinuous galerkin spectral element methods, Computers & Fluids 247 (2022) 105627.
[3] H. Ranocha, Generalised summation-by-parts operators and entropy stability of numerical methods for hyperbolic balance laws, Cuvillier Verlag, 2018.

[Skinnamarink.]

The title to this video stands out from the rest..
Why has this been suggested to me?
What is happening to my...is this the way i must go?