|
|
|
|
|
The corrosivity due to atmospheric conditions can be greatly affected by local conditions such as wind speed and direction, dust, debris, humidity, condensation and electrolytic species. These local conditions can change greatly within a few meters, depending on patterns in air turbulence. One extreme example of local variations due to the corrosivity of a seawater environment is the top deck of an aircraft carrier, where waves and seawater mist are abundant.
An example of local seasonal differences often exist in countries where deicing salts are used in the winter months. The following results have been obtained by exposing CLIMAT coupons in the vicinity of two important highways in Eastern Ontario. The transport and deposition of aerosols are subject to mass transport laws such as convection and turbulent diffusion. Based on these principles, the pattern of aerosol surface deposition can be modeled near obstacles. In such a modeling experiment, it was found that aerosol deposition rates onto and near an obstacle have a very localized structure due to variations in wind speed, wind speed gradients and turbulence.
