The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a multidisciplinary investigation of fault mechanics and seismogenesis along subduction megathrusts and includes reflection and refraction seismic imaging, direct sampling by drilling, in situ measurements, and long-term monitoring in conjunction with laboratory and numerical modeling studies. The fundamental objectives of NanTroSEIZE are to characterize the nature of fault slip and strain accumulation, fault and wall rock composition, fault architecture, and state variables throughout an active plate boundary system. As part of the NanTroSEIZE program, operations during Integrated Ocean Drilling Program (IODP) Expedition 348 were planned to extend and case riser Hole C0002F, begun during IODP Expedition 326 in 2010 and continued during Expedition 338 in 2012, from 860 to 3600 meters below the seafloor (mbsf).Riser operations during Expedition 348 were carried out and deepened the hole to 3058 mbsf, a new maximum depth record in scientific ocean drilling. Operations included installation and cementing of 13 3 ⁄8 inch casing to 2008.9 mbsf and an 11¾ inch liner to 2922.5 mbsf, stabilizing the borehole for future deepening. Reaching this depth required two sidetracking operations from the original Hole C0002F, resulting in the designation of Holes C0002N and C0002P for the successively deeper sidetracks. During drilling, a suite of logging-while-drilling (LWD) and measurement-while-drilling (MWD), mud-gas, and cuttings data were collected over the interval from 2162.5 to 3058.5 mbsf in Hole C0002P, and a partial suite was collected in Hole C0002N. The interval from 2163 to 2218 mbsf was cored with the rotary core barrel (RCB). Planned future riser drilling operations will deepen the hole to penetrate the plate boundary fault at ~4600-5200 mbsf.Additionally, a test hole for a prototype slimhole small-diameter RCB (SD-RCB) coring system, Hole C0002M, was drilled in riserless mode near Hole C0002F. The hole was advanced to 475 mbsf, where four cores were collected to 512.5 mbsf.Overall, Expedition 348 sampled and logged a deep interval in Holes C0002N and C0002P within the inner accretionary wedge, from 856 to 3058.5 mbsf, including a never-before sampled zone in the lowermost ~1 km of drilling. Cores were collected over a 55.5 m interval from 2163 to 2218.5 mbsf. The sampled sedimentary rocks are composed of hemipelagic sediment and fine turbi-

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In this paper are presented a preconditioning technique to be implemented in a three-dimensional explicit compressible code to solve a turbulence flow to steady state regime. A local preconditioning technique with accurate predictions of mixed speed regimes is implemented in the original code, however, for low flow Mach numbers in the boundary layer region the numerical accuracy is lost to the preconditioning code. To improve the numerical solution are suggested a new limit to the preconditioning sensor based on a pressure sensor and is established an explicit flux function to evaluate the preconditioning sensor in the cell fluxes. The preconditioning code is validated for a supersonic case in nozzle and then to a subsonic case is studied the convergence rate for a low Mach number flow. Numerical solutions demonstrated that the changes applied in the original code improves the accuracy and robustness of the code for low speed flows.