Properties of large-scale flow structures in an isothermal ventilated room

In the present work experimental and numerical investigations of the large-scale structures of isothermal air flow in a highly simplified model room are reported and discussed. We compare the measured velocity distribution with direct numerical simulations (DNSs) for the reference Reynolds number Reref = 2.4 × 104, which is based on the maximum inlet velocity and the height of the room. This comparison shows a high similarity concerning the flow structures. Furthermore, we investigate the dependence of the spatial and temporal behavior of flow structures on the Reynolds number from measurements covering a Reynolds number range of 1.0 × 104 ≤ Re ≤ 7.0 × 104. The major finding is that there is a coherent oscillation of the large-scale flow structures, which depends on the Reynolds number. Our findings show that the frequencies of the oscillations are in a good agreement with an empirical model, which describes the auto-oscillation of two colliding planar jets with respect to the Reynolds number and the geometry relations of the inlets. Moreover, the present work indicates that the chosen flow geometry is well suited as a simplified model for problems of room ventilation and can serve as a base for forthcoming studies of non-isothermal cases.