Quantitative thermoviscous Darcy limits in periodic and bounded domains

In this paper, we establish quantitative Darcy limits for a three-dimensional inhomogeneous incompressible fluid with temperature-dependent viscosity and quasi-static thermal feedback. The domain is either the flat torus or a bounded domain with $C^{3,\beta}$ boundary, $0<\beta<1$. The holes have size $\varepsilon^\alpha$ and separation of order $\varepsilon$, with $1<\alpha<3$. Before normalization, the fluid and solid conductivities are $\sigma_\varepsilon^2\kappa_f$ and $\sigma_\varepsilon^2\kappa_s$, where $\sigma_\varepsilon^2\sim\varepsilon^{3-\alpha}$. This scaling preserves the thermal feedback in the limit. For a sufficiently regular reference solution and under an explicit absorption condition, the squared density, velocity and temperature errors are bounded by the weighted initial discrepancy together with $\varepsilon^{\alpha-1}+\varepsilon^{3-\alpha}$ on the torus and $\varepsilon^{\alpha-1}+\varepsilon^{(3-\alpha)/2}$ in a bounded domain. An interface-independent temperature estimate controls the viscosity discrepancy, and a weighted Stokes residual retains the coefficient and cell-pressure commutators. The bounded comparison uses a solenoidal wall correction and cellwise divergence repair. We also construct fixed-parameter microscopic weak solutions. The local strong effective solutions require a separate contraction condition in both settings and stronger boundary regularity in the bounded case.