Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

electrical capacitance tomography model_wrong capacitance reading

Please login with a confirmed email address before reporting spam

hi,
i am working on the simulation of electrical capacitance tomography sensor. i have built the model in comsol4.0a and have simulated it. i have some doubts regarding the same and are listed below.
1. i use the formula 'es.C21' to calculate capacitance in global evaluation. the resultant capacitance value comes with a minus (-) sign.why is it so?
2. i choose plate7 and plate6 as terminals. and calculate the capacitance. when the sensing volume(ie. cavity inside the pipe) contains only air,i get capacitance around 1.944e-12. and when i place a cylindrical object made up of PVC/water/silicon or any other dielectric, i get capacitance value approximately 1.91e-12 which is lesser than the earlier. and this is contradictory to the facet that capacitance of a capacitor increases when a dielectric of a higher dielectric constant is placed between the plate. what could be the mistake?
i am trying to attach the file but there seems to be some problem with the file size limit.the file size is 17MB.is there any alternative?

regards,
Hrishikesh

1 Reply Last Post Jul 22, 2011, 4:38 a.m. EDT

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Jul 22, 2011, 4:38 a.m. EDT
i have shared the model in model exchange under the name 'electrical capacitance tomography sensor'.
i have shared the model in model exchange under the name 'electrical capacitance tomography sensor'.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.