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kylafree

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[求助] FLUENT UDF HELP中关于梯度的描述是什么意思？

大家好，FLUENT UDF HELP中关于Gradient (G)与Reconstruction Gradient (RG）有如下描述：

Gradient (G) and Reconstruction Gradient (RG) Vector Macros

You can access gradient and reconstruction gradient vectors (and components) for many of the cell variables listed in Table 3.2.8. ANSYS FLUENT calculates the gradient of flow in a cell (based on the divergence theory) and stores this value in the variable identified by the suffix _G. For example cell temperature is stored in the variable C_T, and the temperature gradient of the cell is stored in C_T_G. The gradients stored in variables with the _G suffix are non-limited values and if used to reconstruct values within the cell (at faces, for example), may potentially result in values that are higher (or lower) than values in the surrounding cells. Therefore, if your UDF needs to compute face values from cell gradients, you should use the reconstruction gradient (RG) values instead of non-limited gradient (G) values. Reconstruction gradient variables are identified by the suffix RG, and use the limiting method that you have activated in your ANSYS FLUENT model to limit the cell gradient values.

Gradient (G)就是梯度了，Reconstruction Gradient (RG）是什么东西呢？
还有non-limited gradient (G) 又是什么东西呢？
整个后半段都搞不懂是什么意思！！！！求达人帮忙解释一下，感激不尽啊。。。
The gradients stored in variables with the _G suffix are non-limited values and if used to reconstruct values within the cell (at faces, for example), may potentially result in values that are higher (or lower) than values in the surrounding cells. Therefore, if your UDF needs to compute face values from cell gradients, you should use the reconstruction gradient (RG) values instead of non-limited gradient (G) values.

[ Last edited by kylafree on 2012-2-20 at 17:01 ]

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