meshing and boundary condition

no183 · February 24, 2011, 06:08

hey, i already try it, and i able to mesh the face, but while meshing volume, i get this

no183 · February 24, 2011, 06:12

i manage to mesh the face, it is success. But it is different for the volume, i get this error

-mAx- · February 24, 2011, 09:53

you are trying to mesh a complex volume in one shot (you'll never succeed in that way)
you need to split your volume into subvolumes.
And you gave an element size which is very small.
So split your volume and use size fonction for controling your mesh size

no183 · February 24, 2011, 11:01

err, how bro? only 1 volume there

-mAx- · February 25, 2011, 01:25

yes you only have one volume, that's why I adviced you to split it into several small volumes.
>>>Volume/Split

no183 · February 25, 2011, 05:07

so now what the step i have to do?
1) i will spilt the volume. (By the way, how to spilt it? just simply spilt it or spilt it as small and as simple as possible?)
2)mesh those spilted volume 1 by 1.
3)merged them back.
is this the way?

-mAx- · February 25, 2011, 05:14

1- split your volume where you think you need to refine your mesh, and where you think you can apply an hexa mesh (simple geometries like cube, cylinder etc...)
2- yes
3- no, don't merge back your volumes (gambit will glue them together)

no183 · February 25, 2011, 08:12

meaning i dont have to do step 3? gambit automatically joint aka "glue" them back?

-mAx- · February 25, 2011, 08:19

no you don't need step 3

no183 · February 25, 2011, 08:52

and the size function is necessary>?

no183 · February 25, 2011, 08:54

and another question, after i spilt the volume, let say not on the exactly on the boundary, eg like the PSU, in my case it is not purely cube, so i spilt a cube slightly larger then the PSU, is it ok?

no183 · February 25, 2011, 08:59

This is my first volume spilted and mesh, is it ok?

i am using spacing of 2 in order to save time, is it necessary to change to 1?

-mAx- · February 25, 2011, 09:01

you are free to split your domain as you want.
Regarding the size fonction, it is not necessary to use them, but it is very helpful for controling the mesh refinement

chandrasekhar.gullapalli · February 25, 2011, 09:05

Where this size function be generally used?

-mAx- · February 25, 2011, 09:08

grid refinement >> check help

no183 · February 25, 2011, 09:25

I have an idea here, if i can redo all this again, mean before i unite all this volume and subtract to get the fluid domain, can i copy all this volume inividually once? like copy each of PSU, HDD and so on. then after i done all the procedure and want to spilt volume, i just move back the copied item to thier respective locaton, so that i can use spilt volume with volume easy, can i>?

-mAx- · February 25, 2011, 10:16

you want to split your domain with HDD volume, etc...?

no183 · February 25, 2011, 10:30

This is what i done, at the figure, volume 313 is the volume i subtract (the fluid domain). And u can see that volume 314 is the volume which exactly the same (i guess) for the fan heat sink, this (volume 314) volume is i copy the original volume and place at the same location on it before i perform the spilt. However, spilting is success, as shown in figure, but i still fail to mesh volume 314

By the way, in the volume spilt option there is biderectional, connected, and retain, what that 3 option for?

-mAx- · February 28, 2011, 02:15

No the volumes are not the same. Only outer surfaces are the same.
From your flow domain you already substracted this fan. I can see it, because when you pick the whole flow domain, outer surfaces from this fan are highlighted, meaning that the surfaces are outer surfaces from fow domain.
Now splitting the fan volume from the flow domain should fail, since there is no fluid domain inside the fan (hollow).
End even if it worked, I don't understand what you wanted to do...
Once again I don't advice you to import fans.
If you really want to include fans, then create a cylinder which diameter is greater than fan's one, and split your domain with it.
The cylinder will surround your fan and you will be able to pick it for meshing (cylinder substracted with fan).
Then try to mesh it.

no183 · February 28, 2011, 07:55

Oh, ok bro.. I will try that. Meanwhile, for your knowledge, beside the geometry which guided by u, i have do 1 alternative on my own, and it is the simplified version. And, i managed to mesh as shown in the figure below. However, when i import the case file to FLUENT, test.msh in this case, i got the following error. Why?
Building...
grid,
Note: Separating wall zone 3 into zones 3 and 1.
wall -> wall (3) and wall:001 (1)
Warning: ST_Malloc: out of memory.malloc_storage: unable to malloc cell1, size 51779932, t 15, myid 1000000.

Error:
FLUENT received fatal signal (ACCESS_VIOLATION)
1. Note exact events leading to error.
2. Save case/data under new name.
3. Exit program and restart to continue.
4. Report error to your distributor.
Error Object: ()

February 24, 2011, 09:53		#103
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	you are trying to mesh a complex volume in one shot (you'll never succeed in that way) you need to split your volume into subvolumes. And you gave an element size which is very small. So split your volume and use size fonction for controling your mesh size __________________ In memory of my friend Hervé: CFD engineer & freerider

February 25, 2011, 01:25		#105
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	yes you only have one volume, that's why I adviced you to split it into several small volumes. >>>Volume/Split __________________ In memory of my friend Hervé: CFD engineer & freerider

February 25, 2011, 05:14		#107
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	1- split your volume where you think you need to refine your mesh, and where you think you can apply an hexa mesh (simple geometries like cube, cylinder etc...) 2- yes 3- no, don't merge back your volumes (gambit will glue them together) __________________ In memory of my friend Hervé: CFD engineer & freerider

February 25, 2011, 08:19		#109
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	no you don't need step 3 __________________ In memory of my friend Hervé: CFD engineer & freerider

February 25, 2011, 09:01		#113
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	you are free to split your domain as you want. Regarding the size fonction, it is not necessary to use them, but it is very helpful for controling the mesh refinement __________________ In memory of my friend Hervé: CFD engineer & freerider

February 24, 2011, 06:08		#101
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	hey, i already try it, and i able to mesh the face, but while meshing volume, i get this

February 24, 2011, 06:12		#102
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	i manage to mesh the face, it is success. But it is different for the volume, i get this error

February 24, 2011, 11:01		#104
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	err, how bro? only 1 volume there

February 25, 2011, 05:07		#106
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	so now what the step i have to do? 1) i will spilt the volume. (By the way, how to spilt it? just simply spilt it or spilt it as small and as simple as possible?) 2)mesh those spilted volume 1 by 1. 3)merged them back. is this the way?

February 25, 2011, 08:12		#108
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	meaning i dont have to do step 3? gambit automatically joint aka "glue" them back?

February 25, 2011, 08:52		#110
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	and the size function is necessary>?

February 25, 2011, 08:54		#111
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	and another question, after i spilt the volume, let say not on the exactly on the boundary, eg like the PSU, in my case it is not purely cube, so i spilt a cube slightly larger then the PSU, is it ok?

February 25, 2011, 08:59		#112
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	This is my first volume spilted and mesh, is it ok? i am using spacing of 2 in order to save time, is it necessary to change to 1?

February 25, 2011, 09:05		#114
chandrasekhar.gullapalli New Member Chandrasekhar G Join Date: Dec 2010 Location: Chennai Posts: 25 Rep Power: 15	Where this size function be generally used?

February 25, 2011, 09:08		#115
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	grid refinement >> check help __________________ In memory of my friend Hervé: CFD engineer & freerider

February 25, 2011, 09:25		#116
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	I have an idea here, if i can redo all this again, mean before i unite all this volume and subtract to get the fluid domain, can i copy all this volume inividually once? like copy each of PSU, HDD and so on. then after i done all the procedure and want to spilt volume, i just move back the copied item to thier respective locaton, so that i can use spilt volume with volume easy, can i>?

February 25, 2011, 10:16		#117
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	you want to split your domain with HDD volume, etc...? __________________ In memory of my friend Hervé: CFD engineer & freerider

February 25, 2011, 10:30		#118
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	This is what i done, at the figure, volume 313 is the volume i subtract (the fluid domain). And u can see that volume 314 is the volume which exactly the same (i guess) for the fan heat sink, this (volume 314) volume is i copy the original volume and place at the same location on it before i perform the spilt. However, spilting is success, as shown in figure, but i still fail to mesh volume 314 By the way, in the volume spilt option there is biderectional, connected, and retain, what that 3 option for? Last edited by no183; February 25, 2011 at 22:42.

February 28, 2011, 02:15		#119
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	No the volumes are not the same. Only outer surfaces are the same. From your flow domain you already substracted this fan. I can see it, because when you pick the whole flow domain, outer surfaces from this fan are highlighted, meaning that the surfaces are outer surfaces from fow domain. Now splitting the fan volume from the flow domain should fail, since there is no fluid domain inside the fan (hollow). End even if it worked, I don't understand what you wanted to do... Once again I don't advice you to import fans. If you really want to include fans, then create a cylinder which diameter is greater than fan's one, and split your domain with it. The cylinder will surround your fan and you will be able to pick it for meshing (cylinder substracted with fan). Then try to mesh it. __________________ In memory of my friend Hervé: CFD engineer & freerider

February 28, 2011, 07:55		#120
no183 Member no183 Join Date: Sep 2010 Posts: 81 Rep Power: 15	Oh, ok bro.. I will try that. Meanwhile, for your knowledge, beside the geometry which guided by u, i have do 1 alternative on my own, and it is the simplified version. And, i managed to mesh as shown in the figure below. However, when i import the case file to FLUENT, test.msh in this case, i got the following error. Why? Building... grid, Note: Separating wall zone 3 into zones 3 and 1. wall -> wall (3) and wall:001 (1) Warning: ST_Malloc: out of memory.malloc_storage: unable to malloc cell1, size 51779932, t 15, myid 1000000. Error: FLUENT received fatal signal (ACCESS_VIOLATION) 1. Note exact events leading to error. 2. Save case/data under new name. 3. Exit program and restart to continue. 4. Report error to your distributor. Error Object: ()

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
[GAMBIT] 3D boundary layer and meshing problem in GAMBIT 2.4.6	prashanthreddyh	ANSYS Meshing & Geometry	1	December 20, 2011 00:35
Boundary layer meshing problem in Gambit	Crystal	FLUENT	0	June 12, 2009 20:58
GAMBIT problem with 3D Boundary Layer when meshing	Anthony Haroutunian	FLUENT	2	March 26, 2008 02:02
Help Urgent about changing boundary condition	Anjum Naveed	FLUENT	7	August 14, 2006 12:25
Boundary Layer Meshing of a nosecone	Chris	FLUENT	1	March 15, 2005 12:42