Relating hydrodynamic test data with aerodynamics using t-DHI

Abstract

An optical full-field non-invasive technique is introduced to study hydrodynamic interactions within a scale water tunnel as a simile of a wind tunnel. The ad-hoc water tunnel is a transparent chamber that allows the observation of the hydrodynamics generated from the water's interaction with the objects in it. A slow laminar water flow circulates into the tunnel serving as the surrounding media for the samples to be studied. This interaction is monitored with a transmission digital holographic interferometer (t-DHI) that uses a high-speed camera to analyze the changing flow in short periods. As proof of principle, three different tests are presented: the first test is to verify the laminar flow inside the water tunnel. Hence, no sample is inside the chamber. The second uses a barrier placed perpendicularly to the flow to modify the fluid's direction by blocking half of the chamber's path. The last test uses a scale car model, showing how the liquid deviates around the car, similar to the information reported when using a wind tunnel. The t-DHI system used to monitor the ad-hoc water tunnel proves the latter's potential to be used as a wind tunnel in a down-scaled and simple form. For this, as a first-order approximation, consider that a more significant water displacement implies a faster flow; and a slow flow results in small water displacements.