Helmholtz-guided suppression of spurious currents in multicomponent pseudopotential model for high-fidelity immiscible flow in porous media

Accurately modeling immiscible fluid flow in disordered media remains a significant challenge due to the interference of spurious currents. Using the multiple-relaxation-time (MRT) multicomponent pseudopotential lattice Boltzmann method as an exemplar, we perform a Helmholtz decomposition on the anisotropic residual of discrete interaction forces to elucidate its coupling to viscosity pathways. The solenoidal component dissipates through shear viscosity (μ), while the irrotational component engages bulk viscosity (ζ), establishing distinct routes for suppressing spurious currents. Numerical experiments show that employing a 10th-order interaction force markedly reduces the solenoidal share of the residual—by three to four orders of magnitude compared to fourth-order schemes—thereby activating bulk-viscosity control via the energy-mode relaxation parameter (se, sϵ). This approach attains spurious capillary numbers as low as 10−5 and maintains stability at high viscosity ratios, representing up to two orders of magnitude improvement over MRT color-gradient models. The methodology is validated through Laplace pressure tests, two-component Poiseuille flow, Taylor–Bretherton bubble dynamics, and applications in digitized porous media under challenging wettability conditions and high viscosity ratios. From analysis to implementation, the present framework advances high-fidelity multiphase simulations in complex geometries at high viscosity ratios.