I am trying to simulate water heating within a tank, such as water in a hot water cylinder or water in a kettle. I wanted to start with a 2D simulation to reduce the complexity. I have the tank as a surface which is defined as water, with temperature varying properties and an initial temperature of 15DegC. There is a heating element within the tank which generates the heat. I know the dimensions of the element, but as a first approximation I wanted to model it as simply as possible. I also know the total power input generated by the element in W, but not its surface temperature. I have tried several methods. At first I defined a total heating flux through the edges of a rectangle representing the element. I also defined it as a surface and gave it a total heat generation. In all cases the temperatures achieved in the water are much higher than expected. I am very new to CFDesign and I am not sure what I am doing wrong. From the simulation I want to be able to see how the tank heats up and natural convection currents within the volume. At the moment I don't believe the results I am seeing. Any advice how to better tackle the problem, or any comment on what I might be doing wrong would be greatly appreciated.