Simulating cold shear flows on a moving mesh

ABSTRACT Rotationally supported, cold, gaseous discs are ubiquitous in astrophysics and appear a diverse set of systems, such as protoplanetary discs, accretion around black holes, or large spiral galaxies. Capturing the gas dynamics accurately these systems is challenging numerical simulations due to low sound speed compared bulk velocity gas, resolution limitations full disc models, fact that noise can easily source spurious growth fluid instabilities if not suppressed sufficiently well, negatively interfering with real physical present (like magnetorotational instability). Here, we implement so-called shearing-box approximation moving-mesh code arepo order facilitate achieving high local regions differentially rotating address problems. While our new approach offers manifest translational invariance across boundaries continuous adaptivity, demonstrate unstructured mesh introduces unwanted levels ‘grid-noise’ default version code. We show this be rectified by high-order integrations flux over boundaries. With techniques obtain highly accurate results for calculations instability superior other Lagrangian techniques. These improvements also value applications feature strong shear flows.