Hello, I am trying to simulate the electric field inside of a nanochannel filled the water using 2D geometry. The field results from three parallel electrodes (one with applied potential and another two with ground) embedded inside a glass substrate below the channel.
My first idea was to solve a poisson equation using electrostatics in COMSOL. I checked that I get the correct result for a problem I can solve analytically - if the nanochannel was also filled with glass. Then I fill with channel with water and get a resultant electric field.
However, then I realized that water is significantly more conductive than glass, so maybe I should use current conservation equations (electric currents). This gives me a completely different magnitude and shape of electric field, though again for a simple problem of channel filled with glass the results are the same as what I get from electrostatics.
I realize the difference comes from boundary conditions at the water/glass interface, but I am not sure which way gives the correct result.
I attach my simulation file.
Thank you for any advice.