Backward facing step experiment

One of the simplest geometries, which can be relatively easily studied in the experiments and modelled with computational fluid dynamics, is the flow over a backward-facing step. At the Reactor Engineering Division, we cooperated in the European effort to perform numerical simulations of flow and heat transfer in liquid metal over a confined backward facing step. In addition, we also designed and performed our own experiments of water flow in such geometry. The experiment provides validation for a simulation, which provides much more detailed data.

Such simulations are valuable, when we are studying the amplitudes and frequencies of thermal fluctuations that are penetrating into the surrounding walls. Since the thermal fluctuations cause expansion and contraction of the materials in the walls, they are accelerating ageing and shortening the lifespan of the components used for piping. Such experiments and simulations therefore help predicting the safety of existing and new nuclear installations.

Publications:

• B. Zajec, M. Matkovič, N. Kosanič, J. Oder, B. Mikuž, J. Kren and I. Tiselj, “Turbulent Flow over Confined Backward-Facing Step: PIV vs DNS,” Applied Sciences, 11(22), 10582, MDPI (2021); https://doi.org/10.3390/app112210582.
• J. Oder, I. Tiselj, W. Jäger, T. Schaub, W. Hering, I. Otic, and A. Shams, “Thermal fluctuations in low-Prandtl number fluid flows over a backward facing step,” Nuclear Engineering and Design 359, 110460, Elsevier BV (2020); https://doi.org/10.1016/j.nucengdes.2019.110460.
• J. Oder, A. Shams, L. Cizelj, and I. Tiselj, “Direct Numerical Simulation of Low-Prandtl Fluid Flow Over a Confined Backward Facing Step,” International Journal of Heat and Mass Transfer 142, 118436, Elsevier BV (2019); doi: https://doi.org/10.1016/j.ijheatmasstransfer.2019.118436.
• N. Kosanič, B. Zajec, M. Matkovič, J. Oder, and I. Tiselj, “PIV Measurements of Turbulent Flow Over Backward-Facing Step,” in 28th International Conference Nuclear Energy for New Europe — NENE 2019, Portorož, Slovenia, September 9–12, ed. B. Smodiš, Ljubljana, Slovenia (2019).
• B. Zajec, J. Oder, and M. Matkovič, “Two-dimensional PIV Measurements of Water Flow Over a Backward-Facing Step,” in 27th International Conference Nuclear Energy for New Europe — NENE 2018, Portorož, Slovenia, September 10–13, ed. I. Jenčič, Ljubljana, Slovenia (2018).

Page editor: Anil Kumar Basavaraj