Modeling and experimental validation of subgrid scale scalar variance at high Schmidt numbers

[Display omitted] •The subgrid variance of the passive scalar concentration in liquids at different Schmidt numbers was modeled.•Comparisons of different LES models for fluctuations of the passive scalar concentration are shown.•We provide experimental validation of mixing models’ predictions.•Two reactors of a different scale are considered.•Test reactions were applied to investigate mixing effects. This paper is focused on the subgrid closure model for fluctuations of the passive scalar concentration in liquids at different Schmidt numbers. The simulations and experiments were carried out in two impinging jet reactors of a different scale. Distributions of concentration variance, predicted with the use of the literature subgrid scale models, were compared with experimental data obtained by a planar laser induced fluorescence technique. The results of large eddy simulation supplemented with the two subgrid-scale variance models are in very good agreement with experiments. Since the scale similarity LES model described in the literature requires a priori defined value of a model coefficient, further results of the dynamic model are presented in this work.