Dust distribution at t₀ of one of the five simulations for the disc gap at 10 au and δ = 10⁻⁴. The heat map shows the radial profile of the midplane dust density σ_d for different dust mass m_d. The white lines show the m_d corresponding to St = 0.1 (solid) and 0.01 (dotted), respectively. The green and blue lines show the drift and the fragmentation limits, respectively. The dust mass is shown to be limited by the fragmentation limit (≫mm) at the dust trap near 14 au.