划分网格时提示尺寸问题

wowouo

我在使用ANSYS ICEM CFD划分网格时出现问题，提示问题如下面图所示：

这些图片的文字内容如下：
Mesher failed to initialize the size function for non-sweep bodies. Check your size settings to determine whether there are any undesired size requirements on these bodies.

The following entities failed to mesh. The meshes of the bodies containing these entities are not up-to-date.  However, meshing may be successful on the other entities.

The following surfaces cannot be meshed with acceptable quality. Try using a different element size or virtual topology.

The mesher tried to modify the mesh for the following edges that have hard sizing.

The specified body cannot be swept because the following edges and divisions should be switched:

The global min size has been replaced by the mesh size of a premeshed edge or face which is smaller. Please check the premeshed edge or face.

The selective body meshing is not being recorded, so the meshing may not be persistent on an update.  If you want to record the order of the body meshing, please use the Mesh Worksheet to track the meshing steps.  Please see Selective Meshing documentation for more details.

划分网格使用的原图如下

在划分网格之前使用SW2013对它进行了切割，并经过DM15 Generate。划分网格使用curvature and proximity，没有手动设置尺寸与method等。
请教为什么会出现这些问题？如何修正？有时我发现设置了尺寸后反而这些问题？Why?

wowouo

再问一下：ANSYS ICEM CFD网格划分是使用自顶而下还是自下而上的推进顺序更能正确划分呢？从整体到细节还是从细节到整体更不容易出错？