Dissipated Particle Heat
The Dissipated Particle Heat node is available when the Compute particle temperature check box is selected in the physics interface Additional Variables section.
The Dissipated Particle Heat node does not have any inputs, except to specify a domain selection. This feature defines an accumulated variable on the selected domains. It computes a volumetric heat sink if the particles are being heated by their surroundings, or a volumetric heat source if the particles are being cooled by their surroundings. In other words, the purpose of this node is to compute the heat lost or gained by the surrounding fluid as it heats or cools the particles.
This feature accumulates the heat gained or lost by the fluid due to any Convective Heat Losses or Radiative Heat Losses nodes in the Particle Tracing for Fluid Flow interface, but it does not take any contribution from Heat Source nodes, because user-defined heat sources could in principle be derived from a different source than the surrounding fluid, such as radioactive decay or chemical reactions within the particles.
Because the dissipated heat defines an accumulated variable, it uses constant shape functions that are uniform over each mesh element in the domain, but can be discontinuous across boundaries between different mesh elements.
Example: Validation of Energy Conservation in a Coupled Model
If the Particle Tracing for Fluid Flow interface and the Heat Transfer in Fluids interface are solved together in the same study, then this feature can be used to set up a bidirectional (two-way) coupling between them. Add a Heat Source to the Heat Transfer in Fluids interface. Then, in the Heat Source section of the settings window, select Total particle heat source, volumetric (fpt/dph1).
If the exterior boundaries of the fluid domain are all thermal insulators, with no inflow or outflow, then at the end of the Time Dependent study, the following two expressions should give results that are equal in magnitude but opposite in sign:
fpt.sum(fpt.Cp*fpt.mp*(fpt.Tp-at(0,fpt.Tp)))
intop1(ht.Cp*ht.rho*(T-at(0,T)))
where intop1 is an integration coupling over all fluid domains. The expression fpt.Tp-at(0,fpt.Tp) means the difference between the current value of the particle temperature and its initial value.