Simulating cyclic high heat flux loading of divertor cooling finger mock-up

•CFD simulations of high heat flux experiments.•Comparison of temperature profiles from the experiments with the simulated profiles.•Accuracy improved with new materials data and better approximation of heat flux.•Transient analyses of cyclic heat loading using HTC.

The cooling capability of the divertor mock-up under the real DEMO conditions can be tested on the high-heat flux experiments. In this study the high heat flux (HHF) experiments, carried out at Efremov Institute are simulated using the computational fluid dynamics analysis. To accurately reproduce the experimental boundary conditions, the non-uniform distribution of the surface heat flux was taken into account and the heat losses were estimated. Thermal conductivity of the structure material was also found to be an important source of modelling error. The effects of the varied mass flow and inlet temperature boundary conditions on the wall heat transfer coefficient (HTC) distribution are analyzed by the means of steady-state simulation. Based on the obtained HTC, the transient analysis of cyclic surface heating was carried out. The predicted surface temperature cycles on the top of the cooling unit are validated against the experimental data.