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 bojiezhang April 9, 2010 02:37

simulation problem

Preprocessor Messages:
****************************************
** warning - surface area for **
** component 1 is zero **
****************************************

open area mismatch at inter-block boundaries of all blocks
as % of total open area at these mesh boundaries = 8.55612E-11

hello everyone!I have a question about simulation.
first,I do not know what mean for "warning - surface area for component 1 is zero".I set component 1 as a porous component.second ,I have set inter-block by fixed point,why it tells me "open area mismatch ".
so I want to ask if they affact the result and how to solve them?thank you!

 yong April 9, 2010 05:47

Quote:
 Originally Posted by bojiezhang (Post 253882) Preprocessor Messages: **************************************** ** warning - surface area for ** ** component 1 is zero ** **************************************** open area mismatch at inter-block boundaries of all blocks as % of total open area at these mesh boundaries = 8.55612E-11 hello everyone!I have a question about simulation. first,I do not know what mean for "warning - surface area for component 1 is zero".I set component 1 as a porous component.second ,I have set inter-block by fixed point,why it tells me "open area mismatch ". so I want to ask if they affact the result and how to solve them?thank you!

 therockyy April 10, 2010 13:13

Quote:
 Originally Posted by bojiezhang (Post 253882) Preprocessor Messages: **************************************** ** warning - surface area for ** ** component 1 is zero ** **************************************** open area mismatch at inter-block boundaries of all blocks as % of total open area at these mesh boundaries = 8.55612E-11 hello everyone!I have a question about simulation. first,I do not know what mean for "warning - surface area for component 1 is zero".I set component 1 as a porous component.second ,I have set inter-block by fixed point,why it tells me "open area mismatch ". so I want to ask if they affact the result and how to solve them?thank you!
For porous media, when you click "porous properties" under component 1, there will be a list of variables including porosity, X/Y/Z-direction porosity, etc. There is also one blank named "Specific surface area", which has a default value of 0.0. That's the reason why the processor give you such a kind of warning. It won't affect the result.

The open area mismatch like yours won't affect the result either. But try to re-mesh the region will be better. Use uniform mesh size for all mesh blocks or try different mesh size will solve the problem.

Yang

 bojiezhang April 10, 2010 23:08

Quote:
 Originally Posted by therockyy (Post 254094) For porous media, when you click "porous properties" under component 1, there will be a list of variables including porosity, X/Y/Z-direction porosity, etc. There is also one blank named "Specific surface area", which has a default value of 0.0. That's the reason why the processor give you such a kind of warning. It won't affect the result. The open area mismatch like yours won't affect the result either. But try to re-mesh the region will be better. Use uniform mesh size for all mesh blocks or try different mesh size will solve the problem. Yang
Thank you for your help! But when I try to mesh by cell size or the number of celll,the sofeware will adjust it automatically,so the cell size will become different from what I have meshed.
And the cell of inter-bolck is smaller than the out-block,so they are just connected with some nodes,is it the probem ?

 therockyy April 11, 2010 10:00

Quote:
 Originally Posted by bojiezhang (Post 254121) Thank you for your help! But when I try to mesh by cell size or the number of celll,the sofeware will adjust it automatically,so the cell size will become different from what I have meshed. And the cell of inter-bolck is smaller than the out-block,so they are just connected with some nodes,is it the probem ?
Yes, it is a problem. The way I solved this is trying to carefully choose the coordinators of x,y and z direction of the mesh blocks, then choose the appropriate mesh size to make sure the dimension of the mesh block could be divided by the mesh size without remainder. For instance, if I mesh one component in a mesh block with the coordinators of 50mm, 20mm and 10 in 3D, I 'll only choose the mesh cell with size of 5mm, 2mm or even smaller.

When there are two mesh blocks with different mesh size adjacent to each other, I'll try to make sure that the mesh size of one mesh block is the multiply of the other's, like 4mm adhere to 2mm. In this condition, at least nodes of one block will exactly connect with the other one. So, the mismatch is minimized and will keep the influence on the result to a very low level.

My methods sound quite easy but straightforward. I hope it can help you.

Yang

 bojiezhang April 14, 2010 08:45

Quote:
 Originally Posted by therockyy (Post 254174) Yes, it is a problem. The way I solved this is trying to carefully choose the coordinators of x,y and z direction of the mesh blocks, then choose the appropriate mesh size to make sure the dimension of the mesh block could be divided by the mesh size without remainder. For instance, if I mesh one component in a mesh block with the coordinators of 50mm, 20mm and 10 in 3D, I 'll only choose the mesh cell with size of 5mm, 2mm or even smaller. When there are two mesh blocks with different mesh size adjacent to each other, I'll try to make sure that the mesh size of one mesh block is the multiply of the other's, like 4mm adhere to 2mm. In this condition, at least nodes of one block will exactly connect with the other one. So, the mismatch is minimized and will keep the influence on the result to a very low level. My methods sound quite easy but straightforward. I hope it can help you. Yang
Thank you very much!I think it is a good idea,and I wil try it later!

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