** Temperature-Viscosity Calculator V 1.02**
*Copyright © 2021 Henning Umland*

The viscosity of newtonian liquids generally decreases with increasing temperature. The relationship between dynamic viscosity, *η*,
and absolute temperature, T, can be described by the equation

ln *η* = a + b / T^{ c} .

This is a modification of the well-known Andrade equation (c = 1) with improved accuracy over a wide temperature range.
a, b, and c are material constants. The program requires three data points (T_{i} , *η*_{ i}) with
T_{1} < T_{2} < T_{3} to find b and c by iteration (secant method). With these values the programm
calculates a and, optionally, the viscosity at an arbitrarily chosen temperature, T_{4}. Preferably, the latter
should be inside the interval [T_{1} , T_{3}]. Extrapolated viscosities are possible but become less accurate
as one moves farther away from the interval limits. T_{2} should be roughly halfway between T_{1} and
T_{3} for best accuracy. All measurements must be made as accurately as possible since any error will directly affect
the final result. Bad measurements, bad results! The method itself is very accurate. It has been cross-checked with
temperature-viscosity tables for many liquids (water, alcohols, esters, lubricant oils, mercury, molten lead) and with own
measurements (polyesters, molten hydrocarbon resins and asphalts). The systematic error rarely exceeds 1% and usually stays
within the experimental error.

** Input Parameters:**

** Calculated viscosity @ T _{4}:**

Disclaimer: This is experimental software. Although it has been thoroughly tested, it still may contain errors. The author assumes no responsibility for any damage resulting from the use of this software.