Abstract: Commercial CFD programs have been widely used in the thermal and hydraulic simulation of reactors, but they cannot fully meet the application requirements of reactors. Open-source CFD programs have some applications, but, compared with commercial CFD programs, there are still gaps on the comprehensive physical model, calculation accuracy, calculation efficiency and ease of use. In order to better meet the needs of thermohydraulics analysis, it needs a more comprehensive physical model, higher calculation accuracy and better parallel computing efficiency, and it is necessary to develop independent thermal CFD software. This paper describes the design, implementation, and test results of YH-ACT: parallel analysis code of thermohydraulics. Three typical cases are selected, and the correctness of the software is verified by comparing it with the simulation results by typical commercial software Fluent. The software parallel computing scale reaches 400 nodes with 9600 processes. The speedup is 111.7 and the parallel efficiency is 27.9% for the steady-state model. The speedup is 37.2 and the parallel efficiency is 9.3% for the transient-state model.

Key words: thermohydraulics, computational fluid dynamics, parallel algorithm, high performance computing