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[ICEM] Blocking technique. Issues of the day. |
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#1 |
Senior Member
Sergei
Join Date: Dec 2009
Posts: 261
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I have some questions concerning ANSYS ICEM CFD 14.0 Windows 64-bit
1) Having changed something in Blocking structure (moved vertices, for example) and selected checkbox Model -> Blocking -> Pre-Mesh in the Display Control Tree to make ICEM show pre-mesh the following message window pops up ![]() I’d like pre-mesh to be recomputed and showed in visualisation window right after I have selected the checkbox Model -> Blocking -> Pre-Mesh without asking me if I really want it to be recomputed or not. 2) Suppose I want to blank out a lot of blocks from the screen with only few blocks left shown. I go to Model -> Blocking -> Blank Blocks and select which blocks to blank. Is there any reverse-selection-option so that I could select only those blocks which I want to be left shown with all the rest of blocks being hidden? 3) What is the option Pre-Mesh Params -> Match Edges for? ![]() I want Edge_01 and Edge_02 to have identical node distribution parameters: the same number of nodes, the same node spacing, and the same mesh law. So changing of any node distribution parameter of one edge is bound to result in changing conformable node distribution parameter of another edge. I set Edge_01 as a Reference Edge and Edge_02 as a Target Edge, select Link spacing checkbox. Than changing number of nodes distributed along Edge_01 I see nothing happen to nodes along Edge_02, they don’t change at all. How on earth does that Edge Matching work? ![]() 4) I have a mapped block, connected to some other mapped blocks. I want to convert its type from mapped to swept. To do so I go to Edit Block -> Convert Block Type and set top face of the block to be a Swept Face. Top face seems to have disappeared after converting and no mesh is generated inside the block. Output error message is “A serious internal error has occurred. Continuing to work may be dangerous. Please save your work as soon as possible and use a previous copy of your work. If you cannot proceed without getting this message please contact technical support. The following message was designed to aid developers fix the problem: error constructing superblock 303251”. ![]() 5) I have a block with a face split into 3 parts. There’re no adjacent blocks to share this face with (with the exception of those in VORFN). I want 3 parts of the face to be merged into single part. Edit Block -> Merge Faces. ![]() After I select the corner vertices of the 3-part face and click "apply" an error arises:"node's don't form a facemerge face failed" (the same as at the end of my question #7). I had some relevant pictures, but they were lost somehow. 6) I want to split a block face into 2 parts (Split block -> Split Face). I select specific face to split and select the edge where the split will take place. ![]() What I get is the whole block split into 2 blocks with the split direction determined in according to the edge I have selected. ![]() Last edited by Zeppo; March 15, 2013 at 12:16. Reason: Question #7 was reformed |
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#2 |
Senior Member
Sergei
Join Date: Dec 2009
Posts: 261
Rep Power: 21 ![]() |
7) I want to merge 2 blocks into single block (Edit Block -> Merge Blocks)
![]() Merging of the blocks results in a single block which has 6 faces, 4 of them being split into 2 parts each. ![]() I try merging 2 parts of the face into single face by means of Edit Block -> Merge Faces tool. ![]() It says I have to select the corners of the face to merge. So I do, I select 2 corner vertices and get nothing but an error message box. Why doesn’t Merge Face work as expected? ![]() ![]() 8) Aproach recommended (in according to Documentation for ANSYS ICEM CFD 14.0) for mesh generation by means of blocking is a top-down approach. That means I have to create one large global block to encapsulate geometry and than I have to split this global block into several small blocks to capture all the geometry features. This strategy implies I shouldn’t extensively apply such block creation techniques as Extrude Face or From Vertices/Faces (a bottom-up approach). If I don’t follow this recommendation I can incur trouble easily. Creation of blocks in a random manner results in a chaotic, disorderly pale of blocks which are very difficult to handle. All the blocks which are supposed to have been deleted actually have been put into VORF part. You can see in the pictures below what this leads to. ![]() ![]() The problem seems to be due to structured block index system which ICEM have to maintain whatever real block arrangment is. Why Can’t ICEM give up that structured block index system and apply unstructured block index system? It could resolve the issue. I’d like to have the opportunity to create blocks in the unconditioned, arbitrary way. Having a very comlex geometry I can’t imagine beforehand what the block structure will look like. I’d like to have the opportunity to create a block from scratch (for example, from vertices or by extruding a face of any existing block) and than move it to the right place and merge it to the existing blocks. ICEM has such means but they are not considered be be your preferable choice because of imposing a top-down approach on you. ![]() 9) Suppose I have a block and I want to move its vertex (Blocking -> Move Vertices) in a plane which is parallel to the “screen plane” and passes through this vertex. ![]() As I drag the vertex with a mouse cursor it moves along the specific edge as if I have fixed movement direction. But I haven't, as you can see, put any movement constraints in the options for Move Vertices tool. I could resolve the issue if I created local coordinate system with axes oriented in the appropriate directions. Than I could move vertices in that local coordinate system. Is there any way I can rid of such superfluous, troublesome operations? ![]() |
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#3 |
Senior Member
Sergei
Join Date: Dec 2009
Posts: 261
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10) How can I measure such block quantities as the distance between 2 vertices, the length of an edge, the surface area of a face, the volume of a block etc.
11) Some operations on blocks require you to select location. The following window pops up to control selection of the points. What I can’t realize is how some buttons in this window work. ![]() ![]() 12) What if I wanted to create 2D blocks and 3D blocks simultaneously? In the picture below I have a green surface and a blue solid. I want to create 2D blocks for surface and 3D blocks for solid so that 2D mesh is connected to 3D mesh on the node by node base. ![]() First I create 3D block around the solid ![]() Then I go to Create Block -> From Vertices -> 2D and try creating 2D block around the surface. ICEM refuses to do this because the current blocking is 3D. ![]() ![]() 13) I want to create 4 new blocks by means of extruding 4 faces (marked with blue color) of an existing block in the directions normal to each face at once. I.e. each block should be created by extruding in the direction normal to the face it is extruded from. But ICEM can only extrude in one directions determined by the normal to the face selected first. ![]() ![]() |
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#4 |
Senior Member
AB
Join Date: Sep 2009
Location: France
Posts: 323
Rep Power: 22 ![]() |
1) I don’t think so, but that could be a nice feature.
2) I don’t think so, but that could be a nice feature. 3) Edge_01 and Edge_02 must have the same number of nodes. But the nodes distribution can be different (mesh law) if you don’t select « copy parameters » (Edge Params). If you want more info about Match Edges, have a look at the help guide. 4) No idea what’s going on here. 5) 6) 7) I have already asked this question on this forum, and nobody answered. That’s one of the biggest mystery of ICEM ! 8) This is a question for an ANSYS employee. Simon ? ![]() 9) i don’t get it. Why don’t you use the tools such as Fix direction or others ? It can be a superfluous operation to you, but when you have to move vertices which are not in the global coordinate system and also vertices which are in the global coordinate system, ICEM can’t « understand » what you want to do. It’s a computer, you have to work a little bit ! Try the other options of Blocking -> Move Vertices, some are very useful ! 10) Look for the tool Measure Distance (you can apply it on mesh too). For the surface area : Info -> Surface Area. For the volume, right click on a part and then Info. 11) I have never used that tool. 12) Not the right way. First idea, create a 2D block on the block, split the edge and extrude face. Second idea, create a 3D block, and delete the extra blocks. 13) You are right. Last edited by BrolY; March 11, 2013 at 05:05. |
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#5 | |
Senior Member
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Quote:
I can not fid any problem. Tried on similar case and every thing is fine... |
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#6 | |
Senior Member
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#7 | |
Senior Member
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Quote:
Q # 8 . Delete blocks permanently |
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#8 | |
Senior Member
Sergei
Join Date: Dec 2009
Posts: 261
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Quote:
I tried to delete all the blocks from part VORFN. They wouldn't. No dice! They all "survived". If you have to delete a block do you usually delete it permanently? |
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#9 |
Senior Member
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Actually I tried on two face block and it worked ok.
What happens if you turn off VORFN? Blocks are deleted permentally for two reasons: 1. To break the mesh connectivity. 2. To reconstruct VORFN |
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#10 | |||
Senior Member
Sergei
Join Date: Dec 2009
Posts: 261
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Quote:
Quote:
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I'd like to repeat again what I said before:. |
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#11 | |
Senior Member
Sergei
Join Date: Dec 2009
Posts: 261
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Quote:
I'd like to measure block-related things not geometry. The Measure Distance tool is only applied to measure the distance between 2 geometry points. How can I measure the distance between 2 vertices of a block? |
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#12 |
New Member
Ovid
Join Date: Oct 2016
Location: Spain
Posts: 28
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I agree on most points. Nevertheless, I am new in ICEM CFD.
As a recommendation, the user manual of ICEM CFD says that the geometry can be split in simpler parts and later merged. For specially tricky things I find blocking the only way to go. For example meshing solid thickness with layers when complex T-connections exist in fins, for heat conduction problems. GGI of Fluent and other solvers is other solution. On the other hand, blocking scares me as for every geometry it would be like painting the Guernica of Picasso again and again. Just my opinions, I have never tried such things. What would be the recommended approach in general? |
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#13 |
Senior Member
Sergei
Join Date: Dec 2009
Posts: 261
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Hi
I gave up on using ICEM quite a long time ago. Personally I couldn't see ICEM as a tool to be used for real undustry level applications. It needs to be redesigned in so many ways. Personally I don't know where it is now. Maybe it has improved from the version I used. Now in my everyday practice there're so small area in meshing where ICEM's blocking can really compete with other meshing tools. Automatic meshers are the way to go! Last edited by Zeppo; January 6, 2018 at 15:21. |
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#14 |
New Member
Shay
Join Date: Oct 2017
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you can measure the length of the edge with :
blocking-->pre-mesh- params-->edge params --> and then choose the edge you want to measure with the button that i sign in red square in the attached figure. in the next row you will see the length of this edge |
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#15 |
Senior Member
Sergei
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Thanks for pointing out!
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#16 | |
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Yoyu
Join Date: Apr 2011
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#17 |
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Sergei
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Tags |
blocking, icem, merge, mesh, split |
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