Flotherm中加入热管模型后收敛困难

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Flotherm中加入热管模型后收敛困难。

热管具有非常高的有效导热率。因此,当涉及使用温度变量收敛时,可能产生问题。

为避免这些问题,建议用户:

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)

将温度的错误时间步长增加~x20(在“求解器控制”选项卡下)

使用环境变量FLOMAXITFORTEMP
定义新的环境变量FLOMAXITFORTEMP并将其设置为等于任何值

Collapsed object

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.

Open Domain

运行辐射模型时,开放边界如何影响辐射传输?是否计算出交换因子?什么是辐射温度?

o [Model Setup] – Default Radiant Temperature

求解

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: BaseSolutionExchangefacelist (Open with Wordpad)

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