A novel first principle approach will be proposed for dealing with multi-scale laminar, transitional and turbulent flows across weakly porous grids. Taking advantage of the separation of scales due to the small size of the grid pores, MultiMatchGrid will match the large far-grid to the small near-grid scales by means of numerical simulations and artificial intelligence. This will allow to perform high-fidelity simulations for regimes currently inaccessible to DNS and asymptotic theory. The new approach proposed by MultiMatchGrid will be tested against experiments and its potentials for prediction of challenging engineering flows will be assessed by comparing with bench top experiments. Potential applications of our scale matching approach include flow control in pipes, mixers and turbomachinery.