Viscosity Coefficient

Viscosity coefficient, abbreviated as \(\eta\) (Greek symbol eta), also called coefficient of viscosity or absolute viscosity, is the tangential friction force required to preserve a unit velocity gradient between two parallel layers of liquid of unit area.  The greater the coefficient of viscosity the greater the force required to move the layers at a velocity.

 

Viscosity Coefficient formula
\(\large{  \eta = \frac { F_t \; l } { A \; v }  }\)
Symbol	English	Metric
\(\large{ \eta }\)  (Greek symbol eta) = viscosity coefficient	\(\large{\frac{lbf - sec}{ft^2}}\)	\(\large{Pa - s}\)
\(\large{ A }\) = area	\(\large{in^2}\)	\(\large{mm^2}\)
\(\large{ l }\) = distance between the layers	\(\large{in}\)	\(\large{mm}\)
\(\large{ F_t }\) = tangential force	\(\large{lbf}\)	\(\large{N}\)
\(\large{ v }\) = velocity	\(\large{\frac{ft}{sec}}\)	\(\large{\frac{m}{s}}\)