Turbulence face spectral radius

Inviscid contribution

\[\lambda_{\mathrm{inv}} = \frac{A}{2}|v_n|\]

Pure API: TurbInviscidFaceSpectralRadius. Intermediate table: tools/verification/data/turb_inviscid_spectrum_theory.csv (reference face area \(A=2\)).

Diffusive contribution (SA)

\[\nu_{\mathrm{et}} = \frac{\mu_l}{\rho}+\tilde\nu,\qquad \lambda_{\mathrm{diff}} = \frac{1}{Re}\frac{1}{\sigma}\nu_{\mathrm{et}} \frac{A^{2}}{V}\]

Locks: turb_spectrum_policy_test. Contract Workbench entry turb_inviscid_spectrum.

Proves: pure spectral-radius algebra. Does not prove: turb LUSGS case convergence.

Diffusive intermediate curve

Reference geometry in the theory table uses fixed \(1/Re=1\), \(1/\sigma=1\), \(A^2=4\), \(1/V=0.5\), so \(\lambda_{\mathrm{diff}}=2\nu_{\mathrm{eff}}\).

CSV: tools/verification/data/turb_diffusive_spectrum_theory.csv.