Generation of high Reynolds number atmospheric turbulence in a pressurized wind tunnel using an active grid

Mimicking atmospheric turbulence in a lab setting is challenging. This is due to the high Reynolds numbers associated with atmospheric turbulence and the presence of large-scale unsteady structures. This research sheds light on a new method to study atmospheric turbulence in a lab setting. We leverage a pressurized wind tunnel and an active grid to make a high Reynolds number flow with prescribed large-scale unsteady structures. The pressurized wind tunnel uses a heavy gas, SF6, to increase the kinematic viscosity and thus enables us to achieve high Reynolds numbers. The active grid consists of 111 individually controllable paddles, which can excite the flow with extremely high degrees of freedom. We use the active grid to generate large-scale structures that are based on wind velocity data from the AWAKEN field measurement project. We demonstrate that we are able to impose a deterministic mean velocity timeseries on the flow, while smaller-scale turbulence is generated naturally due to the high Reynolds number. As a result, we show we can recreate turbulent atmospheric flows at high Reynolds number (Re_𝝀 ≥ 1000, here, Re_𝝀 is the turbulence Reynolds number) based on field measurement data containing large-scale structures.