For nearly all ductile materials, erosion varies with impact angle and velocity according to:

(12–331)

where is a dimensionless erosion mass, is a model constant, is the particle impact velocity, and is a dimensionless function of the impact angle . For metals, the value of the exponent is generally in the range 2.3 to 2.5 radians.

Finnie’s model of erosive wear relates the rate of wear to the rate of kinetic energy of impact of particles on the surface using the following functions:

(12–332)

The default constants for the Ansys Fluent Finnie Erosion model are only valid for erosion calculations where sand particles hit carbon steel walls. The value of the model constant has been tuned to match the experiment described in [486] in which 326-micron sand particles impact a carbon steel wall at a speed of 104 m/s and therefore is strictly valid only for those specific conditions.