On the viscosity of simple liquids

Summary The pressure and temperature dependence of the viscosity of liquid argon, liquid oxygen and liquid nitrogen are discussed, starting from theArrhenius equation and theDoolittle free volume equation. The experimental results were obtained by measuring the electrical characteristics of a torsionally vibrating quartz crystal, immersed in the investigated liquid and operated at ultrasonic frequencies.

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Zusammenfassung Es werden die Druck- und Temperaturabhängigkeit der Viskosität von flüssigem Argon, flüssigem Sauerstoff und flüssigem Stickstoff ausgehend von derArrhenius-Gleichung und der vonDoolittle diskutiert. Die experimentellen Ergebnisse wurden durch Messung der elektrischen Charakteristik eines in Torsion schwingenden Quarzkristalls, der in die zu untersuchende Flüssigkeit eingetaucht und durch Ultraschall angeregt war, gewonnen.

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Paper read at the Annual Meeting of the German Rheologists, Berlin-Dahlem, May 20–21, 1968.     

Momentum‐based approximation of incompressible multiphase fluid flows

We introduce a time stepping technique using the momentum as dependent variable to solve incompressible multiphase problems. The main advantage of this approach is that the mass matrix is time‐independent making this technique suitable for spectral methods. A level set method is applied to reconstruct the fluid properties such as density. We also introduce a stabilization method using an entropy‐viscosity technique and a compression technique to limit the flattening of the level set function. We extend our algorithm to immiscible conducting fluids by coupling the incompressible Navier‐Stokes and the Maxwell equations. We validate the proposed algorithm against analytical and manufactured solutions. Results on test cases such as Newton's bucket problem and a variation thereof are provided. Surface tension effects are tested on benchmark problems involving bubbles. A numerical simulation of a phenomenon related to the industrial production of aluminium is presented at the end of the paper.