Velocity and pressure visualization of three-dimensional flow in porous textiles

Advances in flow visualization techniques based on optics, such as lasers and digital cameras, have contributed considerably to the development of various flow models. However, the uses of optical techniques for flow visualization in porous media are limited owing to the complexity or opaqueness of the medium. This study demonstrates the utilization of magnetic resonance velocimetry to visualize a flow field in a textile material. By using phase-contrast magnetic resonance imaging, a three-dimensional, three-component velocity vector field was obtained for induced flow through a cut-pile carpet owing to the suction of a vacuum cleaner nozzle. As a result, we were able to experimentally identify the flow-dominant region in the carpet. Specifically, velocity vector plots and flow streamlines facilitated the identification of the flow paths, and indicated that the flow was strongest beneath the narrow walls of the vacuum nozzle. In addition, the pressure field in the carpet was estimated by an omni-directional integral method based on the utilization of the visualized velocity field, which showed where the pressure loss was maximized.