Erros in meshing! I can not understand why!?


#1

Hello All,

I have problems with meshing my solid model (Wye) for multiphase flow simulation. Could you please help me fine meshing the system? I read the log file, but I still can’t find anything showing me the cause of the problem. You can see my project here:

https://www.simscale.com/workbench/?pid=6863290859175928047#tab_0-0


#2

Hey @YB128
can you shear your project link with us?


#3

Hi @Anware

You can find it in my profile. The address is here:

https://www.simscale.com/workbench/?pid=6863290859175928047#tab_0-0

Please let me know if you find it

Thanks


#4

Hi @YB128,

It seems like you didn’t select all the surfaces for the geometry. To do that right click on empty space and assign all surfaces via “Select All”. It should be able to mesh.

Regards,
Barry


#5

Hy @YB128
your current Geometry is not suitable for internal fluid flow simulation.
for internal fluid flow simulation, you have to model the inverse of the pipe (fluid domain of the pipe).
and for better geometry preparation take a note from this Documentation

Regards


#6

Hi @Get_Barried,

I applied your suggestions. However, it still gives me error. You can see it here:

https://www.simscale.com/workbench/?pid=6863290859175928047#tab_0-0


#7

Hi @Anware

Thanks for your time. I did consider the internal surface of the system. I considered all the internal surface of the system (and excluded the outer surfaces) because it is the fluid domain of the pipe. However, it gave me error.


#8

Hi @YB128,

Will try it out.

Let you know if I found a fix.

Regards,
Barry


#9

Thanks @Get_Barried for the help. Please let me know of your results.

I am removing some of the surfaces to simplify the problem. Hope that it helps me to understand the problem.


#10

Hi @YB128,

I was re-reading through what Anware was mentioning about your geometry and what he said was that your geometry is not fully watertight due to one of the uncapped ends of the pipe as you can see here.

This a problem as when you set the material point of the mesher, it needs distinct areas to differentiate between internal and external flow hence the need for a truly watertight geometry. If you were to run this now you would see anomalies in the results or even a straight up error as the material is applied to the entire domain due to the solver not being able to know between what is inside and outside.

Regardless, I’m still attempting to mesh to see if there are any possible other issues, but I would suggest you plug the hole like you did for the other 2 ends and try to mesh again.

Regards,
Barry

EDIT: I’ve managed to get the geometry to mesh successfully as you can see below. Your error was still likely that of not selecting the entire geometry via the Right Click > Select all function. Either way you can attempt to simulate but refer to my earlier statement about the need to ensure a watertight geometry. The project link is here and I’ll leave it up for you, the mesh is under “Barry Mesh”. Do get the new geometry made and meshed! Good luck!


#11

Thanks a lot @Get_Barried for your time and help. I appreciate your kind help. One comment and one question:

One question: As far as I have seen in tutorials, the space inside the pipe should be meshed for CFD application. It is also the internal geometry surfaces, which should be selected as a domain (wall). However, I don’t see any mesh inside the pipe in your file. Am I missing something?


#12

Hi @YB128,

Can you link me the project where you have seen this?

If you’re talking about the space inside the pipe, yes it meshed. All domain within the box is meshed including empty space inside and outside the geometry. You can see this if you download it into a post-processor and take a look at the internal mesh. I’m not exactly sure how to view the mesh before it goes into the solver but if there wasn’t any mesh inside the pipe for internal flow, then you would easily be able to see it in the results and perform the needed corrections afterwards.

Regards,
Barry


#13

Hi @Get_Barried

My perception from the video below (look at 04:10) was that we need to consider only the inner surfaces (the surfaces which are in contact with the fluid) and ignore the other surfaces:

However, I think that you are saying something different and suggesting that I should consider all the surfaces (whether in contact with the fluid or not) in “surfaces with layers” part of the meshing. Am I right or am I misinterpreting?


#14

Hi @YB128

Ah you were referring to the refinement layers at the inlets of the pipe. Yes I have encountered a similar user asking how to obtain such layers from the Automatic Meshing function but unfortunately I have not gotten it to work. I normally use Hex-Dominant Parametric which is significantly much more complex to configure but will be able to obtain the mesh you want for sure.

I will attempt to see if I can figure out a way to obtain this for the Automatic Meshing function but till then you can go ahead and try to get your geometry rectified before we try again.

Cheers.

Regards,
Barry


#15

@Get_Barried

Thanks a lot for all your help. I think I can’t give the right boundary condition to the system because it gives me time step continuity error (once I ran it). I am not sure whether this is because of meshing or not. However, In my first and second boundary conditions, I can select only the wall of the pipe (and not the inlets of the pipe).


#16

Hi @YB128,

I don’t see a simulation error in your project and the current project linked does not have any boundary conditions assigned to it. There isn’t even a proper mesh. Did you create a new project?

Regards,
Barry


#17

Hi @Get_Barried

I ran a simulation on the mesh you kindly provided. You may find it here under “Simulation Designer” and “Run 1”:

https://www.simscale.com/workbench/?pid=4260391973894185909#tab_1-0

Regards


#18

Hi @YB128,

The mesh that I’ve created is not for use because its not proper. That was an attempt to try to get the automatic meshing function working. You will encounter issues as like previously mentioned, there is not proper distinction between the different flow types whether internal or not due to the lack of the caps on all ends of the geometry.

On top of this, there is also a lack of layer refinements at the inlets like that of the video you posted here. Also, the mesh has some weird features like intersecting meshes overlapping each other and a strange gap as you can see below. You need to fix your geometry before we can get this running.

Cheers.

Regards,
Barry