[ANSYS Meshing] Meshing time taking too long

Varshit73 · May 4, 2021, 13:00

Hey,
Im trying to create a mesh for simple flat plate with ramp model for turbulence modelling. Hence i need a mesh density of around 4 million grid points. But my computer has been at it meshing for 6-7 hours now. I did not expect it to take this long. Not sure why.
I am running on Ansys 19.0 and my pc specs are i7 first gen with 24 gb ram with x64 based OS.

Why is it taking so long? What can i do to remedy this?

evcelica · May 4, 2021, 22:13

Did you manually mesh anything, or are you making it do an auto mesh?
Auto mesh will take a lot more time than a manual mesh.

Varshit73 · May 5, 2021, 04:06

I defined a face sizing, body sizing, inflation layers and tetrahedron method. I am not sure if that is auto meshing or manual

evcelica · May 5, 2021, 18:17

This still sounds like it is mostly auto mesh.
For example, when I make a nice structured mesh, I slice the part into bodies (same part though) and define everything using edge sizing, sweep methods, etc. This means I could tell you exactly how many elements it will end of having when complete, there isn't much the mesher has to figure out on its own. This is what I call "manual meshing". With just loose mesh definitions, the mesher has to figure out how to mesh these parts on its own, and will take much longer.

Varshit73 · May 6, 2021, 07:34

Ok. so the recommended way is to define everything in small bodies mesh them together and then combine? Would it be better if i used a meshing software like pointwise to develop the mesh entirely? Would it be faster?
Also, if i define all the characteristics of the mesh and then generate in ansys, what would you expect the meshing time if the number of grid points is around 4-5 million? I have attached my model and what i need the mesh to look like
Im a bit new to CFD, so thanks a ton for all the help.

Varshit73 · May 6, 2021, 07:35

Quote:

Originally Posted by evcelica

This still sounds like it is mostly auto mesh.
For example, when I make a nice structured mesh, I slice the part into bodies (same part though) and define everything using edge sizing, sweep methods, etc. This means I could tell you exactly how many elements it will end of having when complete, there isn't much the mesher has to figure out on its own. This is what I call "manual meshing". With just loose mesh definitions, the mesher has to figure out how to mesh these parts on its own, and will take much longer.

Ok. so the recommended way is to define everything in small bodies mesh them together and then combine? Would it be better if i used a meshing software like pointwise to develop the mesh entirely? Would it be faster?
Also, if i define all the characteristics of the mesh and then generate in ansys, what would you expect the meshing time if the number of grid points is around 4-5 million? I have attached my model and what i need the mesh to look like
Im a bit new to CFD, so thanks a ton for all the help.

flotus1 · May 6, 2021, 08:01

With this fairly simple geometry, creating a block-structured hexahedral mesh in Ansys meshing is pretty straightforward. That should also cut down meshing times to a few minutes.
The general idea is to split your geometry into 3 parts, in a way that each part has 6 rectangular faces. Then apply a few bunching laws on the edges, choose hexa dominant as the meshing method, and that's pretty much it.
There should be many tutorials how to do this on youtube. Search "ansys meshing structured mesh"

This forum might also contain some hints, one example: 3D Multiblock Structured Hexahedral Mesh

Varshit73 · May 6, 2021, 08:07

Quote:

Originally Posted by flotus1

With this fairly simple geometry, creating a block-structured hexahedral mesh in Ansys meshing is pretty straightforward. That should also cut down meshing times to a few minutes.
The general idea is to split your geometry into 3 parts, in a way that each part has 6 rectangular faces. Then apply a few bunching laws on the edges, choose hexa dominant as the meshing method, and that's pretty much it.
There should be many tutorials how to do this on youtube. Search "ansys meshing structured mesh"

Okay thats what im gonna do now. Create a structured mesh. But i could not find what bunching laws are? And also i need to create another mesh for this model plus protrusions in the bottom face, should i use the same methodology there too?

Thanks a ton

flotus1 · May 6, 2021, 08:13

It's been many years since I last used Ansys meshing. So I can't help you with any specifics. Watch a few tutorials, browse the forum for similar topics...

evcelica · May 6, 2021, 15:57

Is your simulation 3D or 2D?
If 2D you don't need much thickness, just sweep mesh 1 element thick.
Slice into 3 bodies.
"Create part" to make it a multibody part.
use sweep meshing and mapped face meshing
assign number of divisions to lines (the same # of divisions for lines which will be swept through)

May 4, 2021, 13:00	Meshing time taking too long	#1
Varshit73 New Member Varshit Jain Join Date: May 2021 Location: Rome Posts: 5 Rep Power: 5	Hey, Im trying to create a mesh for simple flat plate with ramp model for turbulence modelling. Hence i need a mesh density of around 4 million grid points. But my computer has been at it meshing for 6-7 hours now. I did not expect it to take this long. Not sure why. I am running on Ansys 19.0 and my pc specs are i7 first gen with 24 gb ram with x64 based OS. Why is it taking so long? What can i do to remedy this?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
[General] Extracting ParaView Data into Python Arrays	Jeffzda	ParaView	30	November 6, 2023 22:00
[Gmsh] gmshToFoam generates patches with 0 faces and 0 points	Simurgh	OpenFOAM Meshing & Mesh Conversion	4	August 25, 2023 08:58
simpleFoam error - "Floating point exception"	mbcx4jc2	OpenFOAM Running, Solving & CFD	12	August 4, 2015 03:20
Star cd es-ice solver error	ernarasimman	STAR-CD	2	September 12, 2014 01:01
Could anybody help me see this error and give help	liugx212	OpenFOAM Running, Solving & CFD	3	January 4, 2006 19:07

May 4, 2021, 22:13		#2
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,188 Rep Power: 23	Did you manually mesh anything, or are you making it do an auto mesh? Auto mesh will take a lot more time than a manual mesh.

May 5, 2021, 04:06		#3
Varshit73 New Member Varshit Jain Join Date: May 2021 Location: Rome Posts: 5 Rep Power: 5	I defined a face sizing, body sizing, inflation layers and tetrahedron method. I am not sure if that is auto meshing or manual

May 5, 2021, 18:17		#4
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,188 Rep Power: 23	This still sounds like it is mostly auto mesh. For example, when I make a nice structured mesh, I slice the part into bodies (same part though) and define everything using edge sizing, sweep methods, etc. This means I could tell you exactly how many elements it will end of having when complete, there isn't much the mesher has to figure out on its own. This is what I call "manual meshing". With just loose mesh definitions, the mesher has to figure out how to mesh these parts on its own, and will take much longer.

May 6, 2021, 07:34		#5
Varshit73 New Member Varshit Jain Join Date: May 2021 Location: Rome Posts: 5 Rep Power: 5	Ok. so the recommended way is to define everything in small bodies mesh them together and then combine? Would it be better if i used a meshing software like pointwise to develop the mesh entirely? Would it be faster? Also, if i define all the characteristics of the mesh and then generate in ansys, what would you expect the meshing time if the number of grid points is around 4-5 million? I have attached my model and what i need the mesh to look like Im a bit new to CFD, so thanks a ton for all the help.

May 6, 2021, 08:01		#7
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,427 Rep Power: 49	With this fairly simple geometry, creating a block-structured hexahedral mesh in Ansys meshing is pretty straightforward. That should also cut down meshing times to a few minutes. The general idea is to split your geometry into 3 parts, in a way that each part has 6 rectangular faces. Then apply a few bunching laws on the edges, choose hexa dominant as the meshing method, and that's pretty much it. There should be many tutorials how to do this on youtube. Search "ansys meshing structured mesh" This forum might also contain some hints, one example: 3D Multiblock Structured Hexahedral Mesh

May 6, 2021, 08:13		#9
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,427 Rep Power: 49	It's been many years since I last used Ansys meshing. So I can't help you with any specifics. Watch a few tutorials, browse the forum for similar topics...

May 6, 2021, 15:57		#10
evcelica Senior Member Erik Join Date: Feb 2011 Location: Earth (Land portion) Posts: 1,188 Rep Power: 23	Is your simulation 3D or 2D? If 2D you don't need much thickness, just sweep mesh 1 element thick. Slice into 3 bodies. "Create part" to make it a multibody part. use sweep meshing and mapped face meshing assign number of divisions to lines (the same # of divisions for lines which will be swept through)