This paper presents a new mesoscale model simulating the gas phase fluid dynamics and concentration distribution in structured packings, used in absorption and distillation columns. The model describes the structured packing as an arrangement of triangular channel sections and is implemented with an own developed mesoscale simulation code (StructuPack). The velocity field is stored at the cell faces and is driven by pressure, inertial and viscous forces. The coupled continuity and momentum equations are solved with the SIMPLE-algorithm, that is usually applied in CFD solvers. The development of the model is based on fundamental investigations with CFD simulations and experiments, described in the first part of the paper. Particularly, the concentration distribution in a representative geometry of structured packings, a single crisscrossing junction of triangular channels, is analysed. As one result of the fundamental investigations the CFD solver could be validated as a predictive tool with respect to concentration distribution for the laminar regime in structured packings. In the second part, the mesoscale model is described in detail and validated with a scenario of tracer distribution in a packing layer. By means of comparison with CFD simulations of the same scenario it was shown that the mesoscale model has the ability to yield good representations of concentration, pressure and velocity profiles in a structured packing. Thereby the mesoscale computational performance was three orders of magnitudes more efficient with respect to CFD. At the advent of high-performance computing this means that models at intermediate scale are a viable tool to simulate scenarios like maldistribution effects in industrial sized structured packings of distillation and absorption columns. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.