Reply To: Lumerical Heat Difference between Uniform Heat Source and Power Boundary

[kghaffari]

Hi Sabrina,

Great question here. Before I clarify the difference between uniform heat source vs power boundary condition (and the potential reason for the mismatch), please note that you can use both heat sources in a transient simulation:

When using uniform heat source you will have to use a shutter to specify when the source will be turned on. This option is available in HEAT solver under transient tab, and in newer releases also availble in the source itself. On the other hand, with power boundary condition you will have access to it’s time-related properties under it’s own settings. Below are two transient HEAT examples, one using each of the two approaches:

• Metamaterial Microbolometer – Transient with heat source: https://optics.ansys.com/hc/en-us/articles/360041621694-Metamaterial-microbolometer
• Transient heat flow in a graphene-coated glass – Transient with (temperature power) boundary condition: https://optics.ansys.com/hc/en-us/articles/360042273534-Transient-heat-flow-in-a-graphene-coated-glass

There is also a difference between the analysis done with uniform heat source vs power boundary condition; for power boundary condition the heat is emitted from the surface of an object; its boundaries. Therefore, the area of the object is not included in the calculation. You will also notice that the results of HEAT with power boundary doesn’t include the area inside.This is not the case when performing simulations (transient or steady-state) with uniform heat source. This difference could be the reason for the mismatch you see in the results. 

Best regards,

Khash