![]() ![]() ![]() We have also been successful with Windows XP Version 2002, Service Pack 2 using Firefox2.0.0.14 and Internet Explorer. Matlab© scripts for the calculations can be downloaded from this ftp site.įirst, this version of the calculator has been tested successfully in OS X 10.4.11 (Tiger) with browsers Safari 3.1.1 and Firefox2.0.0.14, cutting and pasting from TextEdit.app. Low values of m correspond to strong (Arrhenian-like) melts and higher values of m indicate increasing fragility (non-Arrhenian).įurther details on the calculations are available in the PDF file: Viscosity tutorial.Īn Excel spreadsheet file can be dowloaded here: grdViscosity.xls. Essentially, it is the slope of the viscosity trace taken at T g and can be calculated as: where B, C and T g are specific properties of the individual melts (e.g., rhyolite vs. The "steepnessindex" ( m), as defined by Plazek and Ngai, is a common measure of melt fragility used to track departures from Arrhenianbehaviour and to distinguish strong and fragile melts. Conversely, "fragile" liquids show non-Arrheniantemperature dependence indicating that thermal perturbations are accommodated by continuous changes in melt structure. "Strong" liquids show near-Arrhenian temperature dependence and show afirm resistance to structural change, even over large temperature variations. Melt fragility is a measure of the sensitivity of liquid structure and flow properties to changes in temperature and it distinguishes twoextreme behaviours of glass forming liquids: strong vs. T gis the temperature separating the liquid (relaxed) from the glassy(unrelaxed) state and is taken here as the temperature corresponding toa viscosity of 10 12 Pa-s. The viscosity model can be used to compute derivative transportproperties of glass-forming materials, such as the glass transitiontemperature ( T g) and the fragility ( m) of silicate melts. Dissolved volatile contents vary from about 0 to 8 wt% H 2O and 0 to 4 wt% F. The multicomponent model is calibrated on melt compositions spanning oxide contents (wt. it reproduces observed relationships between melt composition and transport properties such as glass transition temperature ( T g) and fragility ( m).it is capable of accommodating both strong (near-ArrhenianT-dependence) and fragile (non-Arrhenian T-dependence) behaviour ofsilicate melts.it is computationally continuous across the entire compositional and temperature spectrum of the database.the chemical model captures the effects of 10 major and minor oxide components and the volatile components H 2O and F.it spans most of the compositional range found in naturally-occurring volcanic rocks.Where the M's and N's are combinations of mol % oxides. Where A is a constant independent of composition and B and C are adjustable parameters.Ĭompositional dependence is ascribed to B and C as linear combinations of oxide components(mol%) and several multiplicative oxide cross-terms: Temperature dependence of viscosity (η) is modelled by the VFT equation Here we present a model for predicting the non-Arrhenian temperature dependence of viscosity fornaturally-occurring silicate melts at atmospheric pressure (10 5 Pa). Earth & Planetary Science Letters, 271, 123-134 Silicate Melt Viscosity Calculator Silicate Melt Viscosity Calculator Giordano D,Russell JK, & Dingwell DB (2008) Viscosity of Magmatic Liquids: AModel. ![]()
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