There is a great concern for the spread of toxins in the environment, especially in the last 20 years, and since ground water commonly distributes toxins, this topic is naturally at the forefront of environmental engineering. There have been experiments performed which measure fluid flow through a porous medium. For example, one common experimental setup uses stacked beads immersed in a body of fluid. In situations such as this, there are two ways to generate fluid flow. One is to mechanically drive the boundaries of the fluid, creating movement from the viscosity of the fluid.
Temperature can spread through liquids simply by diffusion.
However, it can also spread by convection where heat is transferred by the movement of the fluid itself. This is the course of study of convective fluid flow. As shown in Figure 1, two plates border a porous medium. This medium can either be consecutive layers consisting of rectangular bars, or circularly perforated plates stacked on top of each other with a small space between each disk. A resistive heater heats the lower boundary of the experimental apparatus.