Using POD method in experiments with convection flow on the cube benchmark

¹ Institute of applied physics RAS, Geophysical Research Division, 603950 Ulyanova st. 46, Nizhny Novgorod, Russia
² Nizhny Novgorod State Technical University n.a. R.E. Alekseev, 603950 Minina st. 24, Nizhny Novgorod, Russia

^* Corresponding author: daniil@appl.sci-nnov.ru

Published online: 28 June 2019

Abstract

Investigations of the flow structure on the benchmark “cube” under conditions of natural convection caused by a vertical temperature gradient are performed using a low cost PIV-measuring system with continuous laser. The obtained velocity fields were processed with POD method to obtain typical structures (modes) in the flow. It is shown that the steady flow can be described by combination of the first three modes. It is demonstrated that only starting with the third mode there is a significant change in the spectra of the amplitude coefficients of the modes, the peak shifts to the region of higher frequencies. Thus accounting for this mode is essential for describing turbulent processes in the system and verification of numerical calculations. Comparison with the results of the LES simulation performed using the Ansys CFX package (taking into account the results of processing the experimental data by the POD method) demonstrated good agreement both in the structure of the modes and in their frequency spectra.