Alignment error in engine simulation

sangeeth · June 27, 2018, 08:11

1850 WARNING:
there may be an alignment error.
The maximum dot product of the motion vector with a non-moving triangle's normal vector is 1.166965e-03.
For properly aligned moving surfaces, this dot_product should be less than 5.0e-4

1851 WARNING: The boundary type that appears to not be aligned is WALL, and it is attached to boundary 1, which is moving.

The triangle of maximum alignment error is centered at -6.137263e-03 4.243868e-02 -3.186973e-02

Hi

What can be a solution for this error in engine simulation. I tried to project vertices from the piston to head but I cant find any alignment error. I can run the simulation with this error/warning, but when I turn on monitor points the simulation just crashes.

chaighodke · June 29, 2018, 18:55

Can you please let me know what is boundary 1? This error is typically a geometry related issue. I suggest make sure that you are using correct valve axes. Can you please check that.

sangeeth · June 30, 2018, 09:55

Hi Chaitanya

Thank you for the reply. The error was geometry related. The geometry has just a piston and head. I was able to rectify that by projecting the curve from piston to head.

ibrahimtas · February 4, 2024, 02:29

Hello,
The problem you have encountered is certainly geometry related, but I have not tried rebuilding the methods suggested to solve this problem (such as rebuilding the cylinder liner with the loft command) and unfortunately it did not work.

If you were able to solve this problem, can you describe in detail how you did it?

ksrivast · February 9, 2024, 18:42

Hello Ibrahim,

Cylindrical liners must be rebuilt with the Create > Triangle > Sweep edges option, not the Loft edges option. This will ensure liner triangles are perfectly cylindrical along the piston motion axis provided (Sweep direction). Starting from the piston edge, sweep a single set of liner triangles over a sweep amount slightly greater than your stroke. Connect the open edge of the swept triangles with the open edge on the head with the Loft edges option to close the geometry.

Pay attention to the boundary IDs in the warning messages. If the IDs correspond to the valve boundaries, the same needs to be done for valve stem boundaries along the valve motion direction.

We recommended you take a look at our Piston and Valve Setup training session, available at our downloads page. This session as part of our CONVERGE for IC Engines course guides users on how to construct moving/deforming boundaries.

Sincerely,

ibrahimtas · February 10, 2024, 03:16

Thank you very much for your answer, Kislaya.

I would also have one more question. I am currently using Converge version 3.2. But the license of Converge software belongs to a friend of mine. I access the download and training center with his account. However, I would like to have an account of my own. I registered to the download center, but it is not active, how can I resolve this issue.

ibrahimtas · February 10, 2024, 03:20

Thank you very much for your guidance.

This time when I did this problem as you stated, it worked. However, I do not have access to the download center you mentioned. I have done the registration process, I am waiting for it to be activated for access, but access has not been activated. Can you support me on this issue?

Sincerely regards

June 27, 2018, 08:11	Alignment error in engine simulation	#1
sangeeth New Member Sangeeth Sanal Join Date: Jul 2015 Posts: 3 Rep Power: 11	1850 WARNING: there may be an alignment error. The maximum dot product of the motion vector with a non-moving triangle's normal vector is 1.166965e-03. For properly aligned moving surfaces, this dot_product should be less than 5.0e-4 1851 WARNING: The boundary type that appears to not be aligned is WALL, and it is attached to boundary 1, which is moving. The triangle of maximum alignment error is centered at -6.137263e-03 4.243868e-02 -3.186973e-02 Hi What can be a solution for this error in engine simulation. I tried to project vertices from the piston to head but I cant find any alignment error. I can run the simulation with this error/warning, but when I turn on monitor points the simulation just crashes.

June 29, 2018, 18:55		#2
chaighodke New Member Chaitanya Ghodke Join Date: May 2017 Location: Convergent Science, Madison WI Posts: 29 Rep Power: 9	Can you please let me know what is boundary 1? This error is typically a geometry related issue. I suggest make sure that you are using correct valve axes. Can you please check that. __________________ --------------------------------------------- Chaitanya D. Ghodke, Ph.D. Senior Research engineer Convergent Science Inc. ---------------------------------------------

February 4, 2024, 02:29	Alignment error in engine simulation	#4
ibrahimtas New Member ibrahim Join Date: Jun 2018 Posts: 13 Rep Power: 8	Hello, The problem you have encountered is certainly geometry related, but I have not tried rebuilding the methods suggested to solve this problem (such as rebuilding the cylinder liner with the loft command) and unfortunately it did not work. If you were able to solve this problem, can you describe in detail how you did it?

February 9, 2024, 18:42		#5
ksrivast Senior Member Kislaya Srivastava Join Date: Sep 2017 Location: Convergent Science, Northville MI Posts: 165 Rep Power: 9	Hello Ibrahim, Cylindrical liners must be rebuilt with the Create > Triangle > Sweep edges option, not the Loft edges option. This will ensure liner triangles are perfectly cylindrical along the piston motion axis provided (Sweep direction). Starting from the piston edge, sweep a single set of liner triangles over a sweep amount slightly greater than your stroke. Connect the open edge of the swept triangles with the open edge on the head with the Loft edges option to close the geometry. Pay attention to the boundary IDs in the warning messages. If the IDs correspond to the valve boundaries, the same needs to be done for valve stem boundaries along the valve motion direction. We recommended you take a look at our Piston and Valve Setup training session, available at our downloads page. This session as part of our CONVERGE for IC Engines course guides users on how to construct moving/deforming boundaries. Sincerely, ibrahimtas likes this. __________________ Kislaya Srivastava Principal Research Engineer \| Applications CONVERGECFD

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Internal combustion engine simulation	MichaelC	CFX	5	August 13, 2023 07:03
Tutorial files on SI engine simulation using ANSYS FLUENT	Upendra	FLUENT	0	September 27, 2012 12:57
diesel engine combustion simulation	kebi112358	OpenFOAM	4	September 25, 2012 14:16
Engine simulation (seeking help with method to use)	Geoff Rathbun	Main CFD Forum	4	April 13, 1999 15:19
Question concerning about the flow simulation of a fan in an engine room.	ghlee	Main CFD Forum	3	October 21, 1998 08:05

June 30, 2018, 09:55		#3
sangeeth New Member Sangeeth Sanal Join Date: Jul 2015 Posts: 3 Rep Power: 11	Hi Chaitanya Thank you for the reply. The error was geometry related. The geometry has just a piston and head. I was able to rectify that by projecting the curve from piston to head.

February 10, 2024, 03:16		#6
ibrahimtas New Member ibrahim Join Date: Jun 2018 Posts: 13 Rep Power: 8	Thank you very much for your answer, Kislaya. I would also have one more question. I am currently using Converge version 3.2. But the license of Converge software belongs to a friend of mine. I access the download and training center with his account. However, I would like to have an account of my own. I registered to the download center, but it is not active, how can I resolve this issue.

February 10, 2024, 03:20		#7
ibrahimtas New Member ibrahim Join Date: Jun 2018 Posts: 13 Rep Power: 8	Thank you very much for your guidance. This time when I did this problem as you stated, it worked. However, I do not have access to the download center you mentioned. I have done the registration process, I am waiting for it to be activated for access, but access has not been activated. Can you support me on this issue? Sincerely regards