Gas surface density averaged in azimuth around the primary, as a function of the radial distance, for the base model (α ≈ 0.001, orange curve) and a model with a higher viscosity parameter, α ≈ 0.005 (light blue curve). The black line represents the initial condition. The units of (Σ) are M_A/a². For the adopted system parameters, a density of 10⁻² corresponds to ≈310 g cm⁻². The secondary star is located at pericentre.