Pulse jet mixing (PJM) tests with noncohesive solids in Newtonian liquid were conducted at three geometric scales to support the design of mixing systems for the Hanford Waste Treatment and Immobilization Plant. The test data will be used to develop mixing models. The models predict the cloud height (the height to which solids will be lifted by the PJM action) and the critical suspension velocity (the minimum velocity needed to ensure all solids have been lifted from the floor), two parameters measured during the tests. From the cloud height estimate, the concentration of solids near the vessel floor and the minimum velocity predicted to lift solids can be calculated. The test objective was to observe the influence of vertically downward-directed jets on noncohesive solids in a series of scaled tanks with several bottom shapes. The test tanks and bottom shapes included small- and large-scale tanks with elliptical bottoms, a mid-scale tank with a spherical bottom, and a large-scale tank with a flanged and dished bottom. During testing, the downward-directed jets were operated in either a steady flow condition or a pulsed (periodic) flow condition. The mobilization of the solids resulting from the jets was evaluated based on: the motion/agitation of the particulate on the tank floor and the elevation the solids reach within the tank; the height the solids material reaches in the tank is referred to as the cloud height (HC ).Copyright © 2009 by ASME