Environmental Mass Transfer within A Simple Domain

Below are several examples of mass transfer (diffusion + dispersion + advection) in the environment, specifically groundwater. This first example shows constant diffusion in both X and Y directions:

If the diffusion coefficients are doubled, the result is:

If the diffusion coefficients vary spatially, the pattern changes, as shown in this next animation:

If we double the spatially-varying diffusion coefficient in the X direction only, the result is:

Dispersion is similar to diffusion, only it is tied to velocity (net movement of the groundwater). If we add dispersion to this process, we see:

Adding advection (movement of the contaminant with the groundwater), we see yet another pattern emerge:

These and other examples are covered in this text Remediation

more complex domains