I have sections of porous material which is cut along the axis diametrically. How can we calculate tortuosity using the images of these cut sections? The size of the pores, pore distribution in these cut sections have been determined.
As you know, the tortuosity is the ratio between the length of a flow line between two points (probably the inlet and outlet of a pore or stream line) to the straight line distance between these two points. You could also refer the below link:
http://arxiv.org/pdf/1203.5646.pdf
Yes, of course it is possible. Moreover, most softwares for quantitative analysis of tomography images allow this. However, you should pay attention that the as-obtained values might be lower than the reality if the resolution of the tomograph is not high enough. This situation is very frequently met as soon as you are in presence of small constrictions or poorly connected pores in the medium, for example through thin membranes. These part of the porous skeleton may be too thin to appear in the images and therefore the porosity looks much more connected than it really is. Hence the too low tortuosity.
Alain
Of course, you are likely ultimately interested in the 3-D tortuosity from the 2-D images. If they are serial sections, you can stack them to form a 3-D image and then compute tortuosity using image analysis packages or by computing the 3-D microstructure's conductivity (formation factor). If the microstructure is isotropic, you could reconstruct representative 3-D microstructures by measuring the autocorrelation of the porosity and using Quiblier's technique to produce a 3-D microstrucure with a similar (same) autocorrelation. Software for doing this in the context of computing 3-D permeability of a pore structure can be found at: ftp://ftp.nist.gov/pub/bfrl/bentz/permsolver/.
Keep in mind that Alain's excellent comments concerning adequate resolution, etc. are very valid in general and to this reconstruction method in particular. Good luck.
I think the validity of the excellent comments made earlier will depend to a large extent on your experimental procedure and how you could relate one section to the next, etc. When you say cut sections, some will interpret it as physically cutting sections, doing some sort of surface preparations and 2-D imaging for instance using quantitative back-scattered electron microscopy, etc., and some others will perceive it as sections through a 3-D tomography image. Explaining your experimental set-up and your imaging scheme is key to answering your question with more reliability.