Because of the complex nature of coolant flow in nuclear reactors, current subchannel methods for light water reactor analysis are insufficient. The large eddy simulation method has been proposed as a computational tool for subchannel analysis. In large eddy simulation, large flow structures are computed while small scales are modeled, thereby decreasing computational time as compared with direct numerical simulation methods. Large eddy simulation has been used in complex geometry calculations providing good results in tube bundle cross-flow situations in steam generators. It is proposed that the large eddy simulation method be extended from single- to two-phase flow calculations to help in the prediction of the thermal diffusion of energy between adjacent subchannels.