on the orbital time scales at these small radii. During the simulation, particles in the disc will migrate inwards due to viscous evolution of the disc and are accreted onto the star, resulting in a disc that extends further inwards. This set-up allows us to postpone the expensive calculations towards later times in our simulations, thereby significantly decreasing the duration of our simulations.

We position the disc perpendicular to the flow (see Fig. \[fig:schematics\_eda1\]). This perfect alignment may not occur frequently in nature, but allows to discern the relevant physical processes more clearly. In future work we will investigate the influence of giving the disc an inclination with respect to the flow direction.

### Star {#sec:sink_eda1}

We assume that the mass of the star is concentrated in a single point, which has a mass of $0.4\,{\mbox{$\mathrm{M}_{\odot}$}}$. This corresponds to the typical mass expected in the early disc accretion scenario. The point mass is added as a collisionless particle to the SPH code and we treat it as a sink particle, i.e. it can accrete gas particles that fall within a certain (fixed) radius. The sink particle absorbs the mass and momentum carried by the gas particles it accretes.

We assume 