English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We describe our modelling of the radiatively cooling shocks and their thinshells with various numerical tools in different physical and calculationalsetups. We inspect structure of the dense shell, its formation and evolution,pointing out physical and numerical factors that sustain its shape and also maylead to instabilities. We have found that under certain physical conditions,the circular shaped shells show a strong bending instability and successivefragmentation on Cartesian grids soon after their formation, while remainalmost unperturbed when simulated on polar meshes. We explain this by physicalRayleigh--Taylor like instabilities triggered by corrugation of the dense shellsurfaces by numerical noise. Conditions for these instabilities follow fromboth the shell structure itself and from episodes of transient accelerationduring re-establishing of dynamical pressure balance after sudden radiativecooling onset. They are also easily excited by physical perturbations of theambient medium. The widely mentioned Non-linear Thin Shell Instability, incontrast, in tests with physical perturbations is shown to have only limitedchances to develop in real radiative shocks, as it seems to require a specialspatial arrangement of fluctuations to be excited efficiently. The describedphenomena also set new requirements on further simulations of the radiativelycooling shocks in order to be physically correct and free of numericalartefacts.

On physical and numerical instabilities arising in simulations of non-stationary radiatively cooling shocks