Hello and thanks for quick reply.nnWell I have solid particles inside a fluid and due to that solids optical properties particles generate additional heat. I manage to change particle temperature with custom law of heating. I simply assign a different value of TP_T(tp) by changing the inert heating law. However, I realized that this only changes particles temperature but I also have to modify the energy source in continous phase so that, the extra heat generation I have would be implemented to the continous phase. When I did go through the UDF materials online I found that people are doing what I am trying to do using Custom Law (DPM_LAW) and DPM_SOURCE combined. But when I write my own code for DPM_Source nothing changes, I can not add an extra energy source to continous phase.nS->energy += TP_MASS(tp)*CP_PHOSP*(TP_T(tp)-TP_T0(tp));nI used this but I see no change. But when I erase particle temperature from the equation and applynS->energy += TP_MASS(tp)*CP_PHOSP*20; nI see an extra energy source to continous phase. But since particles temperature (heat generation rate) varies with location, I have to include TP(tp) in the equation.nSo am I understanding the DPM_Source UDF correctly or am I missing something? Or the physical mechanism I try to model requires some other approach.nI hope I manage to express myself clearly. Again thank you for your interest.nPs. Using DPM is important because I do track particle and need particle trajectory information.nn