In the DNV erosion model [4], the erosion rate of particles is determined from:
 | (12–338) |
where
 = material dependent velocity exponent |
 = empirical constant [(m/s)-n] |
 = particle impact velocity [m/s] |
 = dimensionless function of the particle impact angle  (in radians) |
The material constants 
and 
are usually determined by experiments. Recommended values for two typical wall
materials are listed in Table 12.5: Recommended Values for Material Constants .
Table 12.5: Recommended Values for Material Constants
| Material |
|
| Density (kg/m3) |
|---|---|---|---|
|
Steel grades | 2 x 10-9 | 2.6 | 7800 |
|
Titanium grades | 2 x 10-9 | 2.6 | 4500 |
The function 
for steel grades is defined by:
 | (12–339) |
Values for the model constants 
in Equation 12–339 are given in Table 12.6: Model Constants.
