Recent demonstration of Gate-All-Around (GAA) silicon-nanowire (SiNW) MOSFETs has shown an ultimate scaling capability of MOSFET using conventional CMOS-compatible process.  The GAA SiNWs, which has a structure of circular channel, can be studied by 2D device simulations under the cylindrical coordinate.  In this project, various SiNWs will be studied, including length/diameter and doping variations as well as quantum effects.  The result of such simulations will be useful for compact model development, as well as understanding of these emerging transistors for future generation technologies.