Three-dimensional velocity measurements in pulsatile flows via Magnetic Resonance Velocimetry, 2021 MRV Challenge

This presentation is part of the 2021 Magnetic Resonance Velocimetry (MRV) Challenge and represents the results from experiments performed at the Beckman Institute within the University of Illinois at Urbana-Champaign. Experiments were performed on a square cross-section water channel containing a periodic array of rectangular buildings and an injection site in the floor behind one building at a channel Reynolds number of 15,000. The injector was pulsed periodically to produce a transient, highly three-dimensional (3D) flow. Phase-averaged, 3D three-component velocity measurements were obtained using a 3T Siemens scanner with 30 temporal phases across the injection cycle. Additional scan conditions are outlined, as well as an overview of the experimental techniques and equipment used. Detailed results are presented for the flow behavior during several phases of the injection cycle at multiple locations, particularly focusing on complex fluid dynamic behaviors that are highly three-dimensional in nature. The apparatus was also transferred between various research labs worldwide to benchmark transient MRI measurement techniques across independent groups. The results suggest an increased capacity to leverage MRI measurements for flows that are periodic in nature or have repeatable transients.