A recycling / rescaling technique is proposed for Large Eddy Simulations (LES) and hybrid LES/Reynolds-Averaged Navier Stokes (RANS) applications. This method is a generalization of the flat plate technique of Edwards et al. (2008) to a flow affected by multiple walls. Mach 3.5 flow in a square duct is simulated to test the new method, and results are compared to the experimental data of Davis and Gessner (1986). The impact of using a spanwise shifting technique and a quadrant averaging technique within the new recycling / rescaling technique is shown. As a further proof of concept, simulations of flow within a hypothetical isolator geometry are presented.