temperature distribution in a meander structure due to joule heating with calculation of conduction losses in comsol

The idea is to have a meander heater due to joule heating. A 31 * 31 mm coupon having Silicon substrate of 675 um thickness, a 1000 nm thick Silicon dioxide on top of that with the copper meander 500 nm thickness fabricated on top of the Silicon dioxide A voltage of 25 V was required by the structure with a current of 3 A . The temperature was observed on top of the copper structure using a thermocouple and it was found to be in excess of 320 degrees C. The bottom of the Silicon structure too was read as approx 305 degrees C because of conduction. This is ideally used in vacuum but for the temperature distribution it is considered in open air with nothing above and below the coupon. The temperature distribution was observed using a thermal imaging camera, but the same needs to be modelled in comsol. I have to do the same for 3 types of meanders, but i need help for one as I would like to learn too. So a temperature distribution of the below meander (one from the second row in the jpg attached)with a an explanation of steps used to model this would be great as I have no experience in comsol