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-   -   SI engine tutorial error non-positive volumes (http://www.cfd-online.com/Forums/fluent/74112-si-engine-tutorial-error-non-positive-volumes.html)

rackem March 24, 2010 14:49

SI engine tutorial error non-positive volumes
 
While going through the SI engine tutorial I encounter an error when trying to preview the mesh. At around crank angle 570 an error comes up mentioning the negative volume and cuts the preview. When I run the check mesh, it comes up with a couple warnings....

Volume statistics:
Warning: non-positive volumes exist.
minimum volume (m3): -5.334022e-022
maximum volume (m3): 3.089859e-006
total volume (m3): 9.300594e-003

Checking face handedness.
WARNING: left-handed faces detected on zone 41: 3491 right-handed, 2 left-handed.
WARNING: left-handed faces detected on zone 29: 5 right-handed, 2 left-handed.


I followed the tutorial as close as I could up to that point and am not sure where the problem may be from.

The tutorial can be downloaded from this location
http://www.fluent.com/software/sf_me..._si_engine.htm

Thank you

__________________________________________________ ________________________________________________

EDIT: In the transition from the Fluent 6 tutorial to Fluent 12 I missed a simple step that wasn't clear and that was checking the region face box in the remeshing methods option

yubaibai88 March 28, 2010 23:25

I meet the same problem...maybe we should try little time steps,for example set the Crank Angle Time Step to 0.1 in dynamic mesh parameters\in cylinder

rackem March 31, 2010 15:08

were you able to run this correctly? I run into problems when the simulation starts the spray injection and the program freezes.

yubaibai88 March 31, 2010 22:40

I found it unable to process whe start mesh motion in order to preview the dynamic mesh. it appears negetive volume

rackem March 31, 2010 23:06

I fixed this by checking the region face box in the remeshing methods options in the dynamic mesh settings.

yubaibai88 April 2, 2010 23:19

Quote:

Originally Posted by rackem (Post 252585)
were you able to run this correctly? I run into problems when the simulation starts the spray injection and the program freezes.

hi:
I follow all the tutorial tell me to do.but I found the same problem when the simulation starts the spray and the program freeze.did you find how to solve it?

thanks in advance

rackem April 7, 2010 19:19

No I have not found a way around this

yubaibai88 April 8, 2010 21:23

Quote:

Originally Posted by rackem (Post 253677)
No I have not found a way around this

hi rackem:
when I disable "track with fluid flow time step" in define->model->discrete phase->particle treatment,the simulation go down to the end.
have a try,hope it help

rackem April 9, 2010 12:25

My solution still stops at injection. What does your discrete phase model look like. Right now I have Interaction with Continuous Phase and Update DPM Sources Every Flow Iteration checked in the Interaction box. (Note I can't change the Number of Continuous Phase Iterations per DPM Iteration to 5 as it is grayed out and has to be 200) In Particle Treatment I have Unsteady Particle Tracking checked and the Particle Time Step Size (s) at 0.001 (Note the Number of Time Steps is grayed out and listed at 1). In Inject Particles at I have Particle Time Step selected instead of Fluid Flow Time Step. In Physical Models I have Droplet Collision and Droplet Breakup selected in the Spray Model. TAB as the Breakup Model. y0=0 and 2 Breakup Parcels in Breakup Constants.

Thanks for the help!

yubaibai88 April 9, 2010 21:32

1 Attachment(s)
Quote:

Originally Posted by rackem (Post 253973)
My solution still stops at injection. What does your discrete phase model look like. Right now I have Interaction with Continuous Phase and Update DPM Sources Every Flow Iteration checked in the Interaction box. (Note I can't change the Number of Continuous Phase Iterations per DPM Iteration to 5 as it is grayed out and has to be 200) In Particle Treatment I have Unsteady Particle Tracking checked and the Particle Time Step Size (s) at 0.001 (Note the Number of Time Steps is grayed out and listed at 1). In Inject Particles at I have Particle Time Step selected instead of Fluid Flow Time Step. In Physical Models I have Droplet Collision and Droplet Breakup selected in the Spray Model. TAB as the Breakup Model. y0=0 and 2 Breakup Parcels in Breakup Constants.

Thanks for the help!

hi
here is my panel.
obey all the process tutorial tells us to do.
try!

rackem April 14, 2010 17:14

I've obeyed all the processes, but still get it freezes at injection. You do not follow the tutorial because you do not have "Update DPM Sources Every Flow Iteration" checked per your image that you posted. So I'm not sure which rules to follow in the tutorial.

What do you have checked in the "physical models" tab in the Discrete Phase Model?

When I check Droplet Collision in the Discrete Phase Model/Physical Models tab it changes my "Number of Continuous Phase Iterations per DPM Iteration" back to 200 and grays it out.

What version of Fluent are you using? I'm using 12.0.1

yubaibai88 April 14, 2010 20:07

Quote:

Originally Posted by rackem (Post 254649)
I've obeyed all the processes, but still get it freezes at injection. You do not follow the tutorial because you do not have "Update DPM Sources Every Flow Iteration" checked per your image that you posted. So I'm not sure which rules to follow in the tutorial.

What do you have checked in the "physical models" tab in the Discrete Phase Model?

When I check Droplet Collision in the Discrete Phase Model/Physical Models tab it changes my "Number of Continuous Phase Iterations per DPM Iteration" back to 200 and grays it out.

What version of Fluent are you using? I'm using 12.0.1

my version is 6.2.26

ZenCef November 22, 2010 09:06

Is there any solution ? :confused:


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