Experimental Measurement of the Stress Tensor in a Quasi-2D Granular Gas

We study a quasi-2D granular gas that is vertically vibrated. Precise particle tracking from a Phantom V7.2 camera which captures images at 63492 frames per second allows accurate measurement of the momentum transfer from individual collisions as well as from particle motion. With this, we are able to obtain the experimental measurement of the stress tensor. The time-averaged total stress measured shows at least a 95% agreement with the expected hydrostatic balance of the system, indicating that we are adequately resolving the stress. These experimental measurements provide reliable tools that can be directly used for future evaluations of the constitutive equation for stress used in hydrodynamic models.