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Updated: May 20, 2026

Analyzing Mixing Inhomogeneity in a Microfluidic Device by Microscale Schlieren Technique
Published on: June 12, 2015
A comprehensive study of diffusion, thermodiffusion, and Soret coefficients of water-isopropanol mixtures
A Mialdun1, V Yasnou, V Shevtsova
1MRC, Université Libre de Bruxelles, 50, Av. F.D. Roosevelt-CP-165/62, B-1050, Brussels, Belgium.
Abstract:
We report on the measurement of diffusion (D), thermodiffusion (D(T)), and Soret (S(T)) coefficients in water-isopropanol mixtures by three different instrumental techniques: thermogravitational column in combination with sliding symmetric tubes, optical beam deflection, and optical digital interferometry. All the coefficients have been measured over the full concentration range. Results from different instruments are in excellent agreement over a broad overlapping composition (water mass fraction) range 0.2 < c < 0.7, providing new reliable benchmark data. Comparison with microgravity measurements (SODI/IVIDIL (Selected Optical Diagnostic Instrument/Influence of VIbration on DIffusion in Liquids)) onboard the International Space Station and with literature data (where available) generally gives a good agreement. Contrary to theoretical predictions and previous experimental expectations we have not observed a second sign change of S(T) at low water concentrations.
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