SimScale CAE Forum

Multiphase Flow Simulation Fatal I/O Error!


#1

Hi All,

I have been trying to study the flow around a water body in a water tank for weeks and after overcoming errors in different phases of setting up a simulation. Earlier I had a CFL issue very early into the simulation, at present the simulation runs for about 2 secs of physical time and crashes by throwing up either a “Fatal I/O Error” or “CFL exceeds 1” error. I am very close to giving up in running my project on simscale altogether :frowning: Here is a link to my project - https://www.simscale.com/workbench/?pid=4808040960984650438#tab_0-0. Really would appreciate some help. Thanks !

Regards,
Cecil


#2

Hi @cecil_pabbathi!

Guess this is related to the older post from you, right? Let the @PowerUsers_CFD and me have a look at it again and see what causes this.

All the best!

Jousef


#3

Hi @jousefm,

Yes. I did not want to clutter that thread any further and since I created a new project I guessed it would be easier to follow. Besides running into the CFL issue, my force values are insanely high right from the onset !

Cheers !

Regards,
Cecil


#4

Hi @cecil_pabbathi,

Sorry to hear you’ve been running into really difficult problems. I will try my best to help you as much as I can.

So while I’m unsure about the first multiphase simulation you have done, the second one “geom” is the same issue as this post where your outlet should be a positive value rather than negative.

Lets try that first and see if that helps.

Cheers.

Regards,
Barry


#5

Hi @Get_Barried,

Unfortunately it doesnt. I did try simulations with positive outflow conditions but I get a Fatal I/O error. Also that is probably not the correct way to set up my problem because when the surface wave reaches the outlet there is a backflow which messes up the results.


#6

Hi @cecil_pabbathi,

I’ve copied your project over. Let you know tomorrow after I’ve tried it out.

Cheers.

Regards,
Barry


#7

Hi @Get_Barried

Thanks Barry ! Really appreciate it. Hope you have better luck with it than I did :slight_smile:.

Regards,

Cecil


#8

Hi @cecil_pabbathi,

Im doing your simulation now, however just wanted to check whether it is a 6DOF simulation?

If so, what are the full parameters for the solid body 6DOF advanced concepts values? You can check what I need in the copied project here and under “multiphase”, I’ve modified the parameters already just missing values for that bit.

Hope to hear a reply soon.

Cheers.

Regards,
Barry


#9

Hi @Get_Barried,

It doesnt have to be a floating body yet. Definitely at a later stage. For now I am only interested in the drag and lift values of the body. Once we get this running, we can move on to 6dof simulation in my opinion.

Also you might be interested in checking out this simulation of the same case under a different project name. Look for ‘Ver12.5’ https://www.simscale.com/workbench/?pid=961853807733457623#tab_2-0 - Used the same boundary conditions as used in the copied project and the simulations seems to run so far without any errors. The force plots do look very sketchy though. Maybe we can work up from here.

Thanks for the help again. Cheers !

Regards,
Cecil


#10

Hi @cecil_pabbathi,

Please do take a look at one of my runs “Barry Run 1”. While the initial force values are strange due to the need to check the simulation again (likely due to me not initializing the simulation), but after the initial part the values look alright. Is this what you’re looking for?

Cheers.

Regards,
Barry


#11

Hi @Get_Barried ,

Sure.Can i have a link to the copied project ?
Cheers


#12

Hi @cecil_pabbathi,

Just refer to the post above.

I’ve taken a look at the force plots and they are definitely incorrect. Something went wrong somewhere.

Cheers.

Regards,
Barry


#13

Hi @Get_Barried,

Sorry mate. I followed the link on your earlier post which leads me to this https://www.simscale.com/workbench/?pid=4966295548354555931#tab_1-0 . I cant see anything new.


#14

Hi @cecil_pabbathi,

Sorry here is the correct link.

Cheers.

Regards,
Barry


#15

Hi @Get_Barried,

I think its too early to comment on the force values. I ran few free surface simulations on Fluent & CFX, the drag and lift outputs are around 50N & 100N respectively. I think they can be used as a reference to validate our results for the time being. Cheers.

Regards,
Cecil


#16

Hi @cecil_pabbathi,

That simulation I cancelled had around 50N for Drag before I stopped it. You can try to work from my setup, probably initialize the simulation and see if it converges well.

Cheers.

Regards,
Barry


#17

Hi @Get_Barried,

Alright. Thanks Barry. I will keep you posted on the results in that case. Cheers.

Regards,
Cecil


#18

Hi @Get_Barried,

Just a quick note. Adding gravity to the your case set up brings up the CFL issue again. Cheers.

Regards,
Cecil


#19

Hi @cecil_pabbathi,

Please check my simulation again under “Barry Run 2” I have included gravity this time and it is running alright albeit with the same high starting force values before it returns to something more expected.

Just a quick note that I cancelled the simulation rather than it having an error. Not sure why it displayed as error.

Cheers.

Regards,
Barry


#20

Hi @Get_Barried,

Although the simulation runs, the domain here is not being initialized. If you recall this was the same error from my earlier project which was not resolved. However in the ‘Ver12.5’ run https://www.simscale.com/workbench/?pid=961853807733457623#tab_2-0, the domain initializes correctly and the negative flow bc at the outlet works as well but looking at the solution field, the simulation does not behave as expected.

Cheers.

Regards,
Cecil