Edge length ratio at end walls of turbine blade - Mesh Quality

mitra22 · August 27, 2015, 03:46

Hi,
I find that I have a mesh around y+ value of 10. I have gone through the mesh guidelines required for CFX Solver. All the mesh metrics are decent except edge length ratio (270) which is expected to be less than 100. Is it permissible at the endwalls? The mesh calculator in CFD post yields the below values. Kindly advise if my mesh is up to the mark.

Maximum Face Angle
Min: 90 [degree] Max: 131.972 [degree]
Minimum Face Angle
Min: 46.2862 [degree] Max: 90 [degree]
Edge Length Ratio
Min: 1.16725 Max: 270.024
Connectivity Number
Min: 1 Max: 10
Element Volume Ratio
Min: 1 Max: 2.71612

Far · August 27, 2015, 04:19

That is also known as aspect ratio. This can be pretty high in boundary layer and I have used my self up-to 10,000 for double precision solver without any problem.

ghorrocks · August 27, 2015, 09:07

The mesh quality required for a simulation is highly dependant on the simulation. For instance aspect ratios of 10000 in boundary layers can be fine - but for surface tension models if the aspect ratio goes higher than 1.5 you are going to loose a lot of accuracy.

gikamc · January 6, 2021, 20:23

Hello to everyone! I have also meshed my multi-stage turbine model through Ansys TurboGrid. When I use the highest mesh quality with no errors at all, my solution can't reach the convergence criteria. Otherwise, when i use a coarser mesh, aspect ratio error occurs and its value is about 2000-2500. Could I ignore this error and proceed to solution ? Could i check my results by doing a mesh independence study even if the error exists ?

Attach any related references to check if i mished something.

manupanand · October 20, 2022, 04:07

You can refine the mesh and check. Increase or decrease edge split control or change global size factor or add more layer

manupanand · October 20, 2022, 04:08

Quote:

Originally Posted by gikamc

Hello to everyone! I have also meshed my multi-stage turbine model through Ansys TurboGrid. When I use the highest mesh quality with no errors at all, my solution can't reach the convergence criteria. Otherwise, when i use a coarser mesh, aspect ratio error occurs and its value is about 2000-2500. Could I ignore this error and proceed to solution ? Could i check my results by doing a mesh independence study even if the error exists ?

Attach any related references to check if i mished something.

You can refine the mesh and check. Increase or decrease edge split control or change global size factor or add more layer

August 27, 2015, 03:46	Edge length ratio at end walls of turbine blade - Mesh Quality	#1
mitra22 New Member AGNIMITRA Join Date: Jan 2013 Posts: 8 Rep Power: 13	Hi, I find that I have a mesh around y+ value of 10. I have gone through the mesh guidelines required for CFX Solver. All the mesh metrics are decent except edge length ratio (270) which is expected to be less than 100. Is it permissible at the endwalls? The mesh calculator in CFD post yields the below values. Kindly advise if my mesh is up to the mark. Maximum Face Angle Min: 90 [degree] Max: 131.972 [degree] Minimum Face Angle Min: 46.2862 [degree] Max: 90 [degree] Edge Length Ratio Min: 1.16725 Max: 270.024 Connectivity Number Min: 1 Max: 10 Element Volume Ratio Min: 1 Max: 2.71612

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August 27, 2015, 04:19		#2
Far Senior Member Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,558 Blog Entries: 6 Rep Power: 54	That is also known as aspect ratio. This can be pretty high in boundary layer and I have used my self up-to 10,000 for double precision solver without any problem.

August 27, 2015, 09:07		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	The mesh quality required for a simulation is highly dependant on the simulation. For instance aspect ratios of 10000 in boundary layers can be fine - but for surface tension models if the aspect ratio goes higher than 1.5 you are going to loose a lot of accuracy.

January 6, 2021, 20:23		#4
gikamc New Member Join Date: May 2020 Posts: 21 Rep Power: 6	Hello to everyone! I have also meshed my multi-stage turbine model through Ansys TurboGrid. When I use the highest mesh quality with no errors at all, my solution can't reach the convergence criteria. Otherwise, when i use a coarser mesh, aspect ratio error occurs and its value is about 2000-2500. Could I ignore this error and proceed to solution ? Could i check my results by doing a mesh independence study even if the error exists ? Attach any related references to check if i mished something.

October 20, 2022, 04:07		#5
manupanand Member MANU P ANAND Join Date: Jul 2014 Location: Daegu , REPUBLIC OF KOREA Posts: 36 Rep Power: 12	You can refine the mesh and check. Increase or decrease edge split control or change global size factor or add more layer