Viscosity Coefficient

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

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 \(\large{\frac{ft}{sec}}\) \(\large{\frac{m}{s}}\)


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Tags: Coefficient Equations Viscosity Equations