Learning Forum

[Prashank]

I am injecting 64 particles from a inlet using the surface option . I have three outlets & I need to know how many particles escaped from each outlet .
1.is there any option to calculate that?

2 . I am also facing an another problem. My no of incomplete particles keep on fluctuating with the no of iteration . Like on 289th iteration
no of tracked particles= 64, escaped = 63 , incomplete = 1
But the on 300th iteration
No of tracked particles = 64, escaped =56, incomplete= 8
I don't why is this happening.( My model contains vortex formations , if that helps)

[Rob]

Have a look at the results & particle positions: are any particles stuck in the recirculation/vortex zones? 64 is also quite low for statistical purposes: read up on stochastic tracking in the manual(s). 

Have a look in the reporting options (monitors) and you should find a DPM Mass Escape. Assuming all the particles are the same size that should give you enough information. Alternatively use DPM Summary and review the data either as a histogram (Fluent) or via Excel or similar. 

[hjubaer]

My understanding is, the problem you (@Prashank) mentioned is not unusual. The number of incomplete particles will depend on how many steps with what step length factor/length scale Fluent is tracking your particles. If your particle is still trapped inside your domain (e.g. due to vortex formation) after the longest possible tracked length is reached, it will be declared incomplete. As your iteration progresses, there must be some fluctuations in the solution of the flowfield which will lead to fluctuations in the residence time of particles. Therefore, your number of incomplete particles will naturally vary as well, I suppose. 

I would suggest that, you try increasing tracking parameters (e.g. Max Number of Steps) under your DPM settings, in order to let fluent track your incomplete particles to the end. This way you can account for the definite fate for all your injected particles.

I hope that helps. 

Cheers
Hasan

[Prashank]

Thanks mate for your valuable suggestion..I have tried looking into monitors but I couldn't find dpm mass escape ( can you tell me it's location ).I found some mass concentration but it's report only mass concentration not the count of particles.
2.Also the summary option in report is unavailable....
3. I did increase the max no of steps. It seems that the particles are trapped in between the vortex before their trajectories could complete. Is there any option I can found about the location of those particles..

[hjubaer]

My guess is, you are running a steady-state simulation? If you are, then of course you are missing the particle current positions in your particle track summary. 

If transient: Go to Particle tracks>Reporting>Current position and then you can add or remove variables that you want Fluent to report.

If steady state: Try Particle Tracks>Reporting>Step by step and then write the variables in a file

Either way, import the written file in excel and look at the residence time column first (column 1). May be sort the whole sheet according to decreasing residence time. So you now can see your culprits at the top. Column 2 through 4 should give you the particle positions (if the default order was not changed).

Cheers
Hasan

[Ayushman Srivastava]

hi all,

my question is-

I have a transient problem where the dpm model is applied. Particles are escaping from the PRESSURE OUTLETS but in the console, only NUMBER TRACKED is visible.

I want to know number of particles escaped with respect to time from pressure outlets. How can i get it ansys fluent?

[Rob]

DPM out/summary  files. Note, you're tracking parcels and not particles, it's a poor choice of words in the TUI output. 

[Ayushman Srivastava]

How to get DPM out/ summary files?

And my another query is- Solid particles are coming out of the nozzle at high velocity and hitting the skin-like material. I want to see the depth of penetration achieved by the particles within the skin-like material. How to simulate it?

[Rob]

DPM Reports, they're covered in Help, tutorials, Learning & elsewhere on here. 

Impact penetration due to erosion (eg shot blasting) or single particle penetration (bullet)?

[Ayushman Srivastava]

[Ayushman Srivastava]

impact penetration due to multiple particles hitting the skin-like material. How to get it in Ansys fluent? or any other tool I have to use?

 

 

I have another query... How to plot shock wave position Vs time plot in ANSYS Fluent or CFD post-processor for any particular parameter like pressure or mach no. or density?

[Rob]

You may need to look at one of the Explicit codes for that type of penetration. In Fluent we'd look at erosion as a long term problem. You'll need a separate topic for that in the Structures/Mechanical section of the Community. 

Shocks are line/surface effects (2d/3d) so you could plot the shape of the shock on an isosurface using an xy plot and then overlay the lines to see the shock evolution. 

[Ayushman Srivastava]

So for this, first i have to create an isosurface for the entire domain and then i have to run the simulation to see "x Vs t" plot? How to overlay the lines to see the shock?

It is not clear to me

[Rob]

You do need to run the model, then you need to identify the shock. Have you done any of the tutorials? 

[Ayushman Srivastava]

 

Yes sir ..but not related to my problem. Please suggest me the tutorial.

 

[Rob]

You need to run and then review the results. Once you have a data set it'll be clearer what is needed or what can be reported. I'd look at the NACA examples and increase the speed as needed to look at a shock. 

[Ayushman Srivastava]

I performed a 2D simulation of the shock wave in shock tube using ANSYS Fluent tool. Now I want to plot a graph of x-t (x co ordinate vs. time) for the shock wave in the shock tube. It was a unsteady with turbulent model, simulation using the Ansys Fluent. So, is there any way that I can plot x-t graph for the shock wave using the Ansys Post-Processing??

 

Thank You.

[Rob]

There is, but you need to identify the shock to then create the plot. Have a look at iso-surfaces. 

[Ayushman Srivastava]

Hi All

I have to find the dpm velocity magnitude at a nozzle exit. Shall I create a line or a point to see the dpm velocity magnitude?

2nd question is "What should be the report type? area-weighted average or facet maximum or vertex maximun?

[Rob]

Particles hold their own velocity, so I'd use a DPM Report (commonly called .out files) rather than the surface reports. Surface reports may have fields for the DPM fields, but they'll be averaged on that cell/face.