### 6.4.1. Model of Finnie

The wear of a wall due to the erosive effect of particle impacts is a complex function of particle impact, particle and wall properties. For nearly all metals, erosion is found to vary with impact angle and velocity according to the relationship [63]:

| (6–89)

where is a dimensionless mass, is the particle impact velocity and is a dimensionless function of the impact angle. The impact angle is the angle in radians between the approaching particle track and the wall. The value of the exponent, , is generally in the range 2.3 to 2.5 for metals.

Finnie’s model of erosive wear [64] relates the rate of wear to the rate of kinetic energy of impact of particles on the surface, using :

| (6–90)

where:

| (6–91)

#### 6.4.1.1. Implementation in CFX

In CFX, the need to adjust the dimension of to obtain a non-dimensional erosion factor is overcome by specifying:

| (6–92)

where is equal to .

Typical values for are given in the following table:

V0 | Wall Material
--- | ---
952 [m/s] | Aluminum
661 [m/s] | Copper
1310 [m/s] | Mild Steel
3321 [m/s] | Hardened Steel

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