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Mixing-Length Convection

What you are seeing: the Schwarzschild criterion separates convective and radiative regions. Mixing-length theory parameterizes convective transport with α=lm/HP\alpha = l_m / H_P. Toggle the temperature-gradient excess to flip a layer between regimes.

Figure 1. Convective vs radiative regime selector.
∇ - ∇_ad0.05
α = l_m/H_p1.70

WHAT TO TRY

  • Push the gradient excess (nabla - nabla_ad) above zero: the layer flips from radiative to convective by the Schwarzschild criterion and the regime readout switches. That sign change decides whether a layer boils.
  • Raise the mixing length alpha = l_m/H_P: convective blobs travel farther before dissolving and carry more flux. Alpha is the one free parameter 1D stellar models must calibrate.
  • Read the regime indicator as you cross zero: convection switches on abruptly at the Schwarzschild boundary, not gradually.