Thermal convection arises when the Rayleigh number Ra = αgΔTd³/(νκ) exceeds ~1708. Mantle plumes form as hot, buoyant material rises from boundary layers. Simulates 2D convection cells with traceable thermal structures.
Ra = αgΔTd³/(νκ) | Nu ~ Ra^(2/7) | Critical Ra_c = 1708