Jack Rabbit 2: 3D Velocity and Concentration Field Measurements in a Scaled Water Channel Model

A region of the Jack Rabbit 2 Mock Urban Array chlorine tests conducted in fall 2015 at Dugway Proving Grounds in Utah was abstracted via additive manufacturing at 1:188 scale and placed in a water channel. While the actual tests were conducted with pressurized liquid chlorine, this experiment used a single phase, near neutral density fluid as the marked contaminant to see the impact of the array features on the flow field, and to compare to Sonic Anemometry tests that were conducted subsequent to the chlorine tests and also at neutral density. A fully turbulent flow with Reynolds number of 44,000 based on channel hydraulic diameter flowed through the terrain model, while a contaminant was injected through the floor of the domain impacting a splash plate that directed the flow radially away from the source location. Highly detailed three-dimensional measurements with an isotropic resolution of 16 voxels per building height were made throughout the domain. Each measurement consisted of the three components of the mean velocity field as well as the mean concentration field. The measurements were obtained using two different Magnetic Resonance Imaging diagnostics, which are comparatively new techniques to this field. The resulting data set, consisting of over 14 million measurement locations, is analyzed using isosurfaces, streamlines, and contour plots. A detailed discussion of the comparison with field test sonic anemometry data is provided to show the efficacy of the MR diagnostic methods for understanding complex flow fields and for instrument positioning for planned field tests. The data set has full upwind planar data useful for defining inflow boundary conditions. The data set is expected to have utility for computational model validation and for quantifying the accuracy of complex turbulent terrain flow simulations.