Hello,
I am new user of COMSOL and I would like to explain my problem. I have a pellet of magnetite, where I try to heating up with Joule effect. The pellet has 13mm diameter and height of 2mm. Below the pellet I design two small boxes 0.27mm0.27mm0.27mm that I use them as electrodes from copper, and they are placed in a symmetric distance of 4.13mm from the pellet's center of the lower surface. The outer surface of the first electrode, is my (Terminal) Electric Potential where with V=V0=21V and the symmetric place of the other electrode to be my ground. The Tref and the Tamb=500K and I used a Temperature boundary condition where the wall temperature of the pellet is constant T=500K. The upper and lower surface of the pellet within electrodes to be characterized with the default boundary condition of thermal Insulation. My first question is why the temperature profile doesn't give me the expected one. I mean to have a hot zone between the electrodes, and the only hot zone is two half spheres above the electrodes (one and one). The Second question that I want to quote is, why changing the electrodes' dimentions with the same V I have different Q when the material properties is the same.
Thanks in advance.