[vinerm]

Default direction vector for injections is (0 0 1). You need to change it as per your domain axis.

[Swish31]

Now sir even after running the problem for 400 iterations, the points are only visible at the injection spot. why aren't they travelling further down? unsteady particle tracking is switched off.

[vinerm]

Is the direction correctly given? (0 1 0) is different from (0 -1 0). And since the Unsteady particle tracking is disabled, ensure that you have about 50000 steps given as maximum steps.

[Swish31]

Yes sir, I've done both these.

[vinerm]

Does it still show the wrong direction or does it not show any particles. If the direction is still wrong, then try increasing the mass flow rate. This will increase the velocity of the jet. Furthermore, in new versions, there is option to display the injection within Injection setup panel. Click on Update Display and observe the location and direction shown. If it is not correct, then change parameters of the injection to set it right.

[Swish31]

It finally worked.
Thank you sir.
Now im gonna try it with my own geometry.
For this i have to use VOF-DPM right?

[vinerm]

If in your domain, volume fraction is lesser than 10% and atomizer is of orifice type or one of the types available in Fluent, then you don't need VOF-DPM. Just use atomizer model. These are faster and easier.

[Swish31]

Sir i have created my own with blades for little swirl. So i want to try it out.

[vinerm]

Then, you can try it.

[Swish31]

Sir i want to ask in vof-dpm that in my case primary phase is air and seconday phase is water liquid. So in DPM the injection particle will also be water liquid.
This will mean water is injected into water.
This doesn't make sense.......
Can you explain me.

[vinerm]

Injection is into the fluid that you fill the domain with. You can fill it with air or water. However, which phase is converted to particles need to be selected under Phase Interactions > Model Transition.

[Swish31]

Sir
what type of injection should i give, i want the water to be passed through the atomizer at the top and be injected in the cylinder beneath. Should i choose the atomizer outlet as the injection surface?

And what about the injection properties such as velocity and mass flow rate?Do i have to give them or dpm picks it up from the vof model?

https://drive.google.com/open?id=1xl...CZz2QIccjzMZ1U

[vinerm]

Since you are including the injector mesh, you need to provide liquid inlet at the inlet of the injector and then Fluent will solve for the profile at the outlet of the injector, which will behave like an inlet to the surrounding fluid. You need to setup an injection of any time and set its start and stop time to very very high values, say, 1e6 s. This is to ensure that these injections never inject any fluid. Then setup VoF-to-DPM under Phase Interaction > Transition Model.

[Swish31]

Sir what type of injection i should give and at what point exactly, i don't understand and what velocity and mass flow rate should be given for injection?
I will disable unsteady particle tracking.

[vinerm]

That's a dummy injection to enable DPM. It doesn't matter what type of injection you use or what parameters you use.

[Swish31]

So sir the atomizer inlet should be given as the injection point or somplace else?
And since it is a dummy injection the number if particles injected will be zero?
Also, why are we using dpm? as the injection is not doing anything.

[Swish31]

Dear sir
i gave the injection at the end of the atomizer/start of the cylinder with a start time of 0s and end time of 1e+6s.
It shows 0 particles tracked and in particle tracks also it is not showing any particle.

[vinerm]

The VoF-to-DPM procedure requires DPM to be enabled. And DPM cannot be enabled without an injection. Therefore, a dummy injection must be created. It doesn't matter what parameter you use for that. The only parameters that matter are start and stop time and both should be very high. Start time should not be 0, but 1e4 or even more. VoF-to-DPM model predicts the particle size and injects those as particles automatically. That injection is setup by Fluent itself and not by user. User only needs to setup VoF-to-DPM transition under Phase Interactions.

[Swish31]

A start time 1e4 and stop time 1e6 will work?
Also, the injection position should be left as it is? It need not be given right?

[vinerm]

Yes, that's correct.