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 test the operation of two methods for selective application of ArtificialViscosity (AV) in SPH simulations of Keplerian Accretion Disks, using a ringspreading test to quantify effective viscosity, and a correlation coefficienttechnique to measure the formation of unwanted prograde alignments ofparticles. Neither the Balsara Switch nor Time Dependent Viscosity workeffectively, as they leave AV active in areas of smooth shearing flow, and donot eliminate the accumulation of alignments of particles in the progradedirection. The effect of both switches is periodic, the periodicity dependenton radius and unaffected by the density of particles. We demonstrate that avery simple algorithm activates AV only when truly convergent flow is detectedand reduces the unwanted formation of prograde alignments. The new switch worksby testing whether all the neighbours of a particle are in Keplerian orbitaround the same point, rather than calculating the divergence of the velocityfield, which is very strongly affected by Poisson noise in the positions of theSPH particles.

Controlling Artificial Viscosity in SPH simulations of accretion disks