Molecular tagging velocimetry for shocked particle interactions

Knowledge of the unsteady particle kinematics behind a shock wave is important for the understanding of many flows in extreme environments, such as supernovae and the distribution of blast debris in explosions. However, recent measurements of shock-accelerated particles indicate that drag coefficients are an order of magnitude larger than existing models would predict (Bordoloi et al. 2017). This discrepancy cannot be explained by current theory, and simulations in such regimes are extremely challenging. This leaves a need for experimental measurements of the flow around the accelerating particles to explain the unknown unsteady effects. We are developing a velocity diagnostic to measure the flow field behind a shock, targeting simultaneous measurement of the particles’ motion and the carrier phase gas velocity. Techniques like particle image velocimetry are limited by the response time of tracer particles. We overcome this difficulty by using acetone-based molecular tagging velocimetry, with the goal being to implement it simultaneously with a particle tracking system. In this presentation, we will demonstrate the accuracy of our method on simple laminar and turbulent flows, and show our progress toward its implementation on shocked particle flows.