Learning Forum

[andrewl]

Hi,

I'm injecting 700 inert water particles (not parcel) using cone injection (because I need to change spray angle).

• Particles Diameter: 0.1 mm
• Stop time : 0.05s
• Total flow rate 5.86e-5
• Number of stream: 700 (track individual particles)

However, my console showed number tracked ~4000, not sure its particles or parcel. But this is way higher than 700.

Here is my setting, can anyone please help me how can I inject specific number of particles using cone injection, thank you.

 

[andrewl]

Here is what showing in the console

 

Updating solution at time level N...

done.

Injecting 700 particle parcels with mass 2.93e-08 at t = 0.008

number tracked = 3952

Eulerian wall film particles:

absorbed = 697

[Rob]

That will inject 700 parcels per particle time step, and 697 have hit the film. Can you check you don't have splashing on?  Note, we always work with parcels and those parcels may be lighter/heavier than a single particle. 

[andrewl]

is it possible to inject just exactly 700 particles ? 

working with parcel in this case makes me difficult to control how many particles are injected.

Any suggestion how to control the particles injected?

[andrewl]

I resolved the issues by making the injection stop time smaller than the time step, this makes it inject only 700 particles.

[Rob]

No, you have injected 700 parcels. Don't worry about the distinction too much. 

[andrewl]

But I want each parcel have only 1 particles, thats how i can achieve 700 particles injection.

If I only consider it as injecting 700 parcels, the number tracked in the console will  be higher than 700.

Am I understand it correctly? or if you can clarify it a little bit more.

[Rob]

If you set the injection mass and only inject for a short period the parcel and particle mass may be equal, but you're still tracking parcels. Why does it matter if you inject more parcels? The results of those trajectories hitting something/escaping is correct, and having more streams generally gives a more stable result.