GAMMA+ Simulation of Turbulent Heat Transfer Over a Backward-Facing Step

Abstract

GAMMA+ (General Analyzer for Multi-component and Multi-dimensional Transient Application) code is a safety analysis code for nuclear system design and accident analysis. The GAMMA+ code has been developed for the simulation of both one-dimensional and multi-dimensional flows, the latter one being particularly important for components in advanced reactors such as molten salt liquid fuel reactors. In our previous work over the years, we have implemented the standard k-ε model into the GAMMA+ code for multi-dimensional turbulent flow. We have validated a series of cases under turbulent conditions such as flow in a pipe, flow in a plate, flow over a backward-facing step, and flow in a cavity. Most of those validations were performed with adiabatic conditions, and the heat transfer through the fluid was solved for the natural convection in cavities. However, the conjugated heat transfer with a wall has not yet been validated.

In this work, we simulate the flow over a backward-facing step under turbulent conditions to validate the capabilities of the GAMMA+ code. A constant heat flux condition with the wall conduction is chosen for the validation. We compare the results of the GAMMA+ code with a commercial CFD code (CFX) and experimental data. By comparing the results of the GAMMA+ code with the CFX, we verify the standard k-ε model in the GAMMA+ code performs well. The validation results show that the GAMMA+ code predicts the overall trends of the experiment data well in terms of velocity distribution, turbulent intensity distribution, and fluid temperature distribution.