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Verification & Validation
Verification & Validation
The net radiation heat flux of a surface can be found by writing the energy balance equation on the surface.
The three radiation terms on the right hand side of the equation represent different types of radiation associated with a given surface.
The first term is the emitted radiation.
The second term is the reflected radiation.
The third therm is the incident radiation.
The sum of these three terms gives the net radiation heat flux of a surface.
The tabular data from the previous page verifies the energy balance equation.
Mesh Convergence
One way to check the accuracy of the simulation is to refine the mesh and re-run the simulation. The smaller the element in the mesh, the more accurate the simulation will be. The only drawback is longer computation time. To refine the mesh, insert Body Sizing on the specimen and set the element size to 0.001m. Also, enter 0.002m for the element size in the Details of "Mesh". The original mesh has 620 Elements and 4533 Nodes and the new mesh has 1600 Elements and 11204 Nodes.
Shell Net Radiation at end step time (W) | Specimen Net Radiation at end step time (W) | |
|---|---|---|
Original Mesh | 0.2015 | -0.19705 |
Refined Mesh | 0.20344 | -0.19812 |
The net radiation shows very little change as the number of elements is doubled. No further mesh refinement is need.
View Factor
The view factor is calculated for surface to surface radiation. Recall from the radiation equation in pre-analysis, this is an important parameter in computing the radiation between surfaces that are in the same enclosure.
It is difficult to analytically calculate the view factor for this model. Hence, we will use a simplified exercise to show the validity of ANSYS simulation. Proceed to the next step to compare the analytic and ANSYS results.
Go to Exercises