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Posted: 6 years ago 2019年2月7日 GMT-5 11:48

Hi Pien, If I understood you correctly, you simply want to apply AC current through a pair of electrodes stuck in a media. This can be done in COMSOL using the AC/DC module (you should have basic AC/DC capabilities in the base package if you didn't purchase the full module). After you selected the AC/DC physics, choose either a time-dependent domain study or frequency domain. I use time-dependent to accout for joule-heating but if you don't need to, frequency domain makes things 10x easier. Also, my AC fields are not necessarily continuous, so I defined them using an explicit function. Assuming you're using the most basic of AC fields, define your frequency. For the sake of ease later on if you need to redefine something about your electrodes, I suggest you use the explicit selection feature to select each electrode individually as a boundary selection(you can later use these selection tags throughout the rest of your model); do the same with domain selections. Then create a new node under your study and select either terminals for each electrode or electric potential. I use terminals because you can definte either a voltage or current here. From each of the terminals node, define your voltage amplitude for each. If you have an offset, this is where you'll need to definitely define your input functions in the global parameters node. My experience using COMSOL, define everything explicitly as much as you can in the global parameters, functions, domain selections, boundary selections, etc... nodes before you do anything. The more domains and boundaries you have in your models, the more important it is to explicitly select and define everything so it is much easier to keep track of things down the road. If your model geometry was built using COMSOL's own assembler/mesh, and you have few domains, maybe you don't need to define it as granular. Hope this helps and good luck! Let me know how it goes. Ed