Experimental study of the impacts of forced vibration on thermodiffusion phenomenon in microgravity environment

The SODI-IVIDIL (Selectable Optical Diagnostics Instrument-Influence of Vibrations on Diffusion of Liquids) project was performed on board the International Space Station to study the possible influences of a wide range of forced vibration on thermodiffusion measurements in a condition of microgravity subjected to three temperature differences. In this study, the effects on a thermodiffusion experiment of increasing the Gershuni number (Gs) from zero to Gs ∼3 × 103 with a constant temperature gradient of 15 K were studied for the first time. While many investigations have been done studying thermodiffusion phenomena in a microgravity condition, and preliminary discussions on IVIDIL objectives have been proposed, only a few works can be found in the literature that address the result of this project. ISS experimental results were obtained that were based on optical digital interferometry in a reduced gravity environment. Nine runs of water and isopropanol with a negative Soret coefficient and a temperature difference of 15 K were analyzed as test cases in this study. However, results indicate a maximum separation and Soret coefficient for the case with a minimum Gershuni number, and different concentration profiles and separation patterns were observed. Remarkably, when Gs = 1.5 × 103, the maximum separation may not occur at the end of diffusion time.