Validation of Turbulent Momentum Mixing of MATRA-S Code for CNEN 4x4 Single Phases Flow Mixing

The calculation of various turbulent flow mixing coefficients has been done to evaluate the exit velocity distributions for corner, side and central subchannels with the measurement results for each subchannel. Furthermore, the effect of the turbulent flow mixing coefficient will be as the main point of this study. CNEN4x4 is an experiment which was done in unheated assembly under single-phase flow condition which had been performed by Studsvik Laboratory to obtain information about the heat transfer due to the flow turbulent mixing between adjacent subchannels under a single-phase flow regime. MATRA-S predicted accurately the flow velocities profiles along the axial direction, by comparing the measured data using the optimum TDC value with the maximum percentage error which turned to be 3.0 %. The comparison with CNEN4x4 measurement was successfully validated by using the appropriate model applied in MATRA-S code which is EM turbulent model and optimizing its coefficient.