# Slurry Viscosity

## Definition - What does Slurry Viscosity mean?

Slurry Viscosity can be defined as the product of dynamic viscosity of slurry, the liquid (Ul) and relative viscosity (Ur). It can be expressed relatively to the viscosity of a liquid phase.

The unit of slurry viscosity is (Pa.s) because the relative viscosity is dimensionless and dynamic viscosity of slurry has a unit of (Pa.s).

## Petropedia explains Slurry Viscosity

Depending on the size and concentration of the solid particles, several models exist that describe the relative viscosity as a function of volume fraction of solid particles.

In the case of extremely low concentrations of fine particles, Einstein's equation may be used:

In the case of higher concentrations, a modified equation was proposed by Guth and Simha which takes into account interaction between the solid particles:

Further modification of this equation was proposed by Thomas from the fitting of empirical data:

Where values of A = 0.00273 and B = 16.6

In the case of high shear stress (above 1 kPa), another empirical equation was proposed by Kitano and the relative viscosity in this case is:

Where A = 0.68 for smooth spherical particles.

Once the relative viscosity is calculated, the values are put into the below equation to find slurry viscosity: