An adaptive lattice Boltzmann method for wake effect on drag force of interactive particles in supercritical water

Supercritical water gasification (SCWG) is a highly promising technology. A fundamental aspect of SCWG involves the flow of supercritical water (SCW) around interactive particles, which is inherently complex due to the presence of the wake effect. This study numerically investigates particle wake characteristics and wake-particle interactions in high-viscosity supercritical water (SCW) via an adaptive lattice Boltzmann method (LBM, N / D = 30, coarse-fine ratio 0.025:0.060) to support supercritical water gasification (SCWG) reactor optimization. The adaptive LBM effectively balances accuracy and efficiency, resolving SCW's steep viscosity gradients and fine wake structures well. Interparticle distance ( L / D ) is the dominant factor for particle drag, affecting trailing particles far more significantly, with three interaction regimes (strong: L / D = 0–2, moderate: 2–4, weak: ≥4). SCW's high viscosity amplifies wake overlap at L / D ≤ 2, minimizing trailing particle pressure drag and suppressing vortex shedding; increasing L / D weakens shielding, elevates drag, and makes trailing particles behave like isolated ones. Interparticle angle raises drag ratios, inducing distinct vortex structures at 30°–60° and 60°–90°, with identical drag at 90°. SCW wake symmetry and vortex shedding show Re-dependent transitions, with critical Re = 92 corresponding to the minimum trailing particle drag ratio. A drag ratio correlation with L / D and Re is also established. This work provides a reliable numerical tool for SCW particle interactions and theoretical guidance for SCWG reactor optimization, with future work focusing on particle swarms and experimental validation.