A device and method for creating hydrodynamic cavitation in fluid is provided. The device can include a flow-through chamber having a first portion and a second portion, and a plurality of baffles provided within the second portion of the flow-through chamber. One or more of the plurality of baffles can be configured to be selectively movable into the first portion of the flow-through chamber to generate a hydrodynamic cavitation field downstream from each baffle moved into the first portion of the flow-through chamber.