Combined density gradient and velocity field measurements in transient flows by means of Differential Interferometry and Long-range $$\varvec{\upmu }$$ PIV.

In the present study, Long-range Microparticle Image Velocimetry ( $$\upmu$$ PIV) and Differential Interferometry (DI) are combined in a novel manner to enable both velocity and depth-integrated density gradient field measurements using the same laser pulse for both recordings. In the present work, temperature-driven boundary layer flows could be successfully determined to an accuracy of $$\Updelta T=0.17\,\hbox {K}$$ with a spatial resolution of $$405\,\upmu \hbox {m}$$ for interference and $$101\,\upmu \hbox {m}$$ for $$\upmu$$ PIV measurements. The DI measurements are refraction compensated, and both temperature and velocity fields are compared with results from numerical simulations. [ABSTRACT FROM AUTHOR]