Case 1: Apply 0.1 V Voltage AC on one terminal surface (0.1 sin(314t), apply 0 V voltage on another terminal surface, goal is AV specific volume joule heat.

Case 2: Apply 0.1 V voltage AC on one termial surface (0.1 sin(314t), apply 0.1 sin(314t-2π/3) voltage on another terminal surface, goal is same AV specific volum joule heat.

Question is : normal call  case 1 voltage is single phase voltage, case 2 is two phase voltage,   theroy calculation, Joule heat generate of case 2 is 3 times than that of case 1,(Line voltage is 1.732 times phase voltage, wattage is 3 times)

however simulation calculation  joule heat of case 2 is 5.6 times than that of case 1. I don't know the reason?

see attachment: joule heating model