Longitudinal (acoustic) wave-energy flux at t = 40 min for a vertical cut through the domain at Y = 19 Mm, and horizontal cut at Z = 2 Mm. Fast and slow magnetosonic shocks, which are identified through a threshold on ∇ ⋅ v, are indicated in red and green colours, respectively. For the horizontal slice, shocks are highlighted at a range of heights throughout the chromosphere (not just from Z = 2 Mm). The plasma β equal to one surface is highlighted with a thin dashed black line.