Here’s a smorgasbord of DIY experiments from Dianna at Physics Girl. Some are fluidsy, some aren’t, but all of them give you a chance to stretch your science muscles at home. Personally, I think she saved the best for last with her laser-acoustics demo! (Video credit: Physics Girl)
Tag: laser-induced fluorescence
Laser-Induced Fluorescence
One of the challenges of experimental fluid dynamics is capturing information about a flow that varies in three spatial dimensions and time. Experimentalists have developed many techniques over the years–some qualitative and some quantitative–all of which can only capture a small portion of the flow. The photos above are a series of laser-induced fluorescence (LIF) images of an airfoil at increasing angles of attack. The green swirls are from an added chemical that fluoresces after being excited with a laser. In this case, the technique is providing flow visualization, showing how flow over the upper surface of the airfoil shifts and separates as the angle of attack increases. The technique can also be used, however, to measure velocity, temperature, and chemical concentration. (Image credit: S. Wang et al.)
Laser-Induced Fluorescence
As demonstrated in the video above, lasers can be used to excite molecules into a higher energy state, which will decay via the emission of photons, causing the medium to glow. This laser-induced fluorescence is utilized in several techniques for measurements in fluid dynamics, including planar laser-induced fluorescence (PLIF) and molecular tagging velocimetry (MTV). In these techniques a flow is usually seeded with a fluorescing material–nitric oxide is popular for super- and hypersonic flows–and then lasers are used to excite a slice of the flow field. The resulting fluorescence can be used for both qualitative and quantitative flow measurements. Here are a couple of examples, one in low-Reynolds number flow and one in combustion. (Video credit: L. Martin et al./UC Berkeley)
