Measurement of eddy diffusivity in bubble column and validation based on the intermittency models

Abstract

This paper discusses methods for the estimation of eddy diffusivity using the instantaneous velocity–time data measured in a bubble column reactor. In the first method, the analysis uses the eddy isolation methodology with a correction for the bubble–beam path interruption in the data. The correction is estimated from the observation of the time-varying data acquisition rate in the time series. The method is oblivious to the type of anemometer used for the data acquisition and is useful for all kinds of multiphase measurements. For validation of the results, we have proposed a strategy based on the synergistic combination of energy spectrum and the intermittency models for revealing different stages in the turbulent cascades. The method uses the actual scales in the cascade for the estimation of eddy diffusivity and hence such a combination has resulted in a robust validation tool. The comparison of the estimations based on the standard k– ɛ model and integral length scales is also discussed.