Time instant of the swirling strength λ in a slice of dimension 9.6 × 2.6 × 2.8 Mm³ of the whole physical domain of the numerical simulation. The red contour indicates the surface of optical depth τ₅₀₀ = 1. The yellow contour corresponds to the isosurface of plasma-β = 1. Swirls with a period larger than 10 min (λ < 2.09 × 10⁻² Hz) are not shown and the values λ > 1 Hz are saturated. This rendering has been produced with ParaView (Ahrens et al. 2005).