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Diffusion Coefficient

Posted: Fri Feb 05, 2010 8:35 pm
by sarahd
Hi,

I am hoping to be able to use STANMOD to be able to back out diffusion coefficients from Concentration vs. distance data I have from 1-D diffusion only experiments conducted in small sandstone prisms. Should I use CXTFIT inverse? I am unsure on what to put for the parameters. I would appreciate some help with this.

Thanks,
Sarah

Posted: Sat Feb 06, 2010 7:44 am
by ntoride
Sarah:
CXTFIT is a program based on analytical solutions for the convection dispersion equation. If you need a pure diffusion equation, you need another solution (but it should be easy to derive the solution). Or CXTFIT can evaluate the CDE with a very small v value. An example can be found in the FIG73A project in the "Inverse" workspace. Please carefully read the CXTFIT manual as well. Nobuo