Jet loop reactors (JLRs) have been shown to offer outstanding mixing and heat-transfer per-formance, but their strongly coupled internal–external circulation makes hydrodynamic designnon-trivial. Conventional finite-volume Computational Fluid Dynamics (CFD) remains compu-tationally demanding, thus limiting its value for routine optimisation. This study presents thefirst validated Lattice Boltzmann Method (LBM) simulation of a single-phase, top-nozzle JLRdriven at industrially relevant specific power inputs of 2.24–5.83 kW m−3. The flow was resolvedwith a D3Q19-LES scheme and halfway bounce-back walls on a locally refined Cartesian lattice.A physical time span of 20 seconds was simulated in less than 54 hours on a single NVIDIARTX 4090, thereby demonstrating the graphics processing unit (GPU) friendly scalability of themethod.The simulation successfully reproduced the measured radial velocity profiles and internal volumeflow rates within experimental uncertainty, with the remaining deviation falling below eight percent. Error analysis indicates that the quadratic lattice combined with the halfway bounce-backwall model slightly narrows the effective annular cross-section, thereby systematically accelerat-ing the loop flow. A complementary simulation, with the grid rotated by 45°, suggests that gridorientation may amplify or mitigate this artefact. However, the magnitude of the orientationeffect could not be conclusively quantified within the present study and is therefore identified asa subject for further investigation.Despite this limitation, the solver captures all key hydrodynamic features, including the forma-tion of a fully turbulent jet core and the weak sensitivity of circulation to power input. Fur-thermore, it shortens turnaround time by approximately two orders of magnitude in comparisonwith representative Reynolds-averaged Navier-Stokes (RANS) studies. The validated workflowprovides a robust foundation for future two-phase extensions aimed at predicting gas holdup andinterfacial mass transfer, thereby facilitating a rapid simulation path for a broader class of loopreactors.