Numerical simulation of bubble columns: LES turbulence model and interphase forces blending approach

Abstract

Abstract In this study the large eddy simulation (LES) turbulence approach was adopted to simulate bubble columns in a wide range of gas velocity and operating conditions, in order to obtain a general model capable of simulating with satisfactory accuracy and moderate computational resources most industrial cases. The model used to carry out the numerical simulations stems on the Eulerian–Eulerian two-fluid model. A particular feature of the model is the implementation of a blending approach, which is adopted to describe the phase inversion at the surface of the gas–liquid mixture. An extended investigation of the main LES turbulence models was conducted at high gas velocity to find the most suitable one for the investigated test cases: the Smagorinsky model accounting also for the bubble induced turbulence provided the most notable results in a wide range of operating conditions. The validity of the model was also confirmed at lower gas velocity. A comparison with the standard k–e RANS model showed that the LES methods produced significantly more accurate results, in particular for systems with non-symmetrical gas feed, even though the computational time required is marginally higher.