The virtual reality image on the website was generated to show the end result of using Pore-Ped with Pore-Cor, and to show how Pore-Cor can display the location of different types of fluid in the simulated void structure.

To start with, we dialed in a clay soil texture into Pore-Ped, specifically 15% sand, 29% silt, 56% clay, bulk density 1.2 gm per cm3, organic carbon content 0.2 %. This generated a water retention curve, based on the U.K. Soil Survey pedo-transfer function published by T.Mayr in Geoderma.

Then we used the Simplex to find a good fit to the water retention curve, as shown in the graph. (Click here to see the state of the Simplex control screen at the end of the run.) Notice that the water retention curve does not need to be smoothed (although in this case the pedo-transfer function uses a two-zone Brooks-Corey function). A new, more robust fitting algorithm seeks the best fit point by point, and therefore the water retention curve also does not need to go over the whole modelled range of 0 to 100% non-wetting phase.

Having fitted the curve, it is then straightforward to generate the structure. To illustrate the way the behaviour of different non-wetting fluids can be modelled, we forced in a non-wetting phase (nwp) such as oil until accessible throats as small as 30 um were filled. Then we occluded the structure with a colloidal suspension containing particles of 1 um diameter. Finally, we intruded air to displace water, to a tension of 2 um.

You will notice that the structure has all pores of the same size. The simplicity of this is deceptive - there is very subtle structuring in the positions and sizes of throats. For other materials, such as sandstone, the pores have a much wider range of sizes.  

Click 'Back' below to return to the Virtual Reality details, from where you can enter the Virtual Structure yourself. See if you can find some Colloidally Occluded throats - they are difficult to find - you need to tour around, and get up close to the finest of throats, which will only show themselves when you get very near them.