This paper considers the question of how to evaluate Euler-Euler simulations of macro-mixing in two-phase bubble columns. Here, the idea is to perform tracer experiments (jump responses) both experimentally and also numerically. In both cases the resulting data is then analyzed on the basis of the convection-dispersion model. Given that the integral quantities gas hold-up, axial dispersion coefficient (i.e. Bodenstein number) and mean residence time show sensitivity with respect to the physical phenomena, the applied turbulence models (i.e. k-� and SST) and the boundary conditions, respectively to their numerical consequences, this approach provides a means to evaluate the quality of sophisticated mathematical models and their numerical realization.