使用双精度求解器（double precision solver “求解器控制”选项卡） 使用“共轭残差”选项（conjugate residual “求解器控制”选项卡）
Radiation is calculated based on the temperature difference between objects. Therefore for the software to compute these temperature differences it must know the temperatures of the objects partaking in the Radiative exchange. In fixed temperature cuboids (collapsed or uncollapsed) the temperature of the object is explicitly set. Therefore these objects partake in Radiation but can only pass heat to other objects cooler than themselves. They cannot become warmer or cooler because their temperature is fixed by you. Objects set to have a fixed heatflow give out energy to the neighbouring grid cells but do not have a temperature calculated within them. Therefore there is insufficient data for the software to compute its radiation calculation and therefore they will not partake in the radiative exchange. Collapsed objects can only take part in the radiation calculation if they are set to be fixed temperature. If set to be conducting they cannot take part in the radiation calculation because they don't have grid-cells within them to store the temperature data.
Note: These objects will all act as obstructions to radiation, inhibitting the view factor between other radiating objects.
- All radiating geometry inside the domain will radiate towards “infinity outside the domain”, the domain boundaries.
- Therefore exchanges factor are calculated.
- Domain boundaries are ideally “black”.
- Radiation is always a two-way process. Hence, if the radiation temperature of the domain boundary is higher than the body temperatures inside there will be a positive net radiation heat flow into the domain and heat will be added. If the radiation temperature is lower than the body temperatures heat will be extracted from the system.
- The temperature used to calculate the radiation of each domain boundary is set in the Project Manager in
o [Model Setup] – Default Radiant Temperature
- Ambient Attributes may be used to overwrite the above settings with Radiation Temperature other than the Default Radiant Temperature. You may use different Ambient Attributes for different sides and hence different Radiation Temperatures on different sides of the domain.
Domain boundaries which are set to “Symmetry” are adiabatic. To prevent violation of the energy conservation, one side will be opened to radiation transfer (but only for radiation transfer!) automatically. In this case there will be a warning displayed in the Message Window.
用于计算每个域边界辐射的温度在项目中设置[Model Setup] – Default Radiant Temperature
Insufficient Memory < Exchange Factor Calculation performed abnormal exit > The total radiating faces is above the limit.
The number of radiating faces is limitating to 120000 radiating faces by default. If the number of radiating surfaces exceeds this value, an exception is thrown and the EFG aborted.
To increase the number of radiating faces using Environment variable, you can set
System environment variable: EFGFACELIMIT System environment value: Number
When the calculation is done, the number of radiating faces can be found on the first line of the following file: BaseSolution\Exchange\facelist (Open with Wordpad)