Evaluation of turbulence kinetic energy budget in turbulent flows by using a photobleaching molecular tagging velocimetry

Understanding turbulence kinetic energy (TKE) budget in gas-liquid two-phase bubbly flows is indispensable to develop and improve turbulence models for the bubbly flows. Simultaneous measurement of velocity and velocity gradients with spatial resolution smaller than the Kolmogorov scale is required to evaluate the TKE budget experimentally. We therefore proposed a molecular tagging velocimetry based on photobleaching reaction (PB-MTV) and applied it to turbulent flows in a square duct to demonstrate the possibility of evaluation of TKE budget. Although the accuracy of measured velocity and velocity gradients were examined in the previous study, the accuracy of the TKE budget has not been examined yet due to lack of information on the TKE budget. In this study, we measure TKE budget in a turbulent water flow in a square duct by using the PB-MTV at the same turbulent Reynolds number condition as DNS data provided by Iwamoto, and compare the measured data with the DNS data to validate PB-MTV for evaluation o...