[Swish31]

So i have created an atomizer and want to see the spray pattern of my water atomizer. I only want to see the spray pattern. Which model should i use Multiphase or DPM?
To analyse the flow after the outlet of the atomizer, i need to have some sort of space which i have to model to see the pattern?So i should i just model a space and unite that space and the atomizer at the outlet of the atomizer?
Supposedly if i have a cubical space, i choose 5 of the walls as outlet and 1 wall of the cube becomes wall.
Kindly guide me.
Thanks

[vinerm]

Do you have initial droplet size distribution with you? If yes, then you can use DPM. There are a few atomizer models available in Fluent. If your atomizer can be represented by one of those, then also you can use DPM. However, if that is not the case, then you will have to use VOF-DPM combination wherein Fluent can predict the size distribution.

[Swish31]

Dear Sir
I tried out the VOF-DPM model but in the phase interaction window there is no option to couple both of them.
Also can you tell me how i should go about modelling the spray area?
My atomizer is a plain orifice atomizer so i should simply select that and give the boundary conditions as per the problem?

[vinerm]

If your atomizer is plain orifice type, then you do not need VOF-DPM; this interaction is not enabled via Interaction panel, but you don't need it for your case. You can use the inbuilt atomizer model in DPM.

[Swish31]

Yes it is plain orifice type.
So DPM should work.
Can you tell me how to go about the injection part?
I am spraying water-liquid into air.
Thanks

[vinerm]

Once you have enabled DPM, under the Injections you have to choose the atomizer model under the Injection Type. Default would be Single. Then, provide all the relevant details and select Material for the injection.

[Swish31]

In materials, i want water-liquid or droplets. Only water-vapour is coming.
Please tell me regarding the modelling of the area in which the spray goes.

[vinerm]

You have to select Inert Type Particle and not Droplet. Material has to be water-liquid. Continuous phase has to be air because spray is in the air. So, whole domain will be air except for the DPM.

[Swish31]

Could there be any problem in my software as water-liquid is not available

[vinerm]

You can add any fluid at any time. Just go to Material Panel for Particles and then go to Fluent Database to add water-liquid.

[Swish31]

Have done that, still no good. It is still not showing up in materials in injection.

[vinerm]

Delete the Injection and create a new one.

[Swish31]

Dear Sir, now only anthracite is available.

[vinerm]

You have to select the material when you create an Injection before clicking on Apply. Once clicked, you won't have option to change it until and unless you change or add a material in the Material Panel. Easiest is to change the name of the material to water and change the properties to that of water as well.

[Swish31]

So i will choose anthracite and rename it as water and change the properties.


My atomizer looks like this

https://drive.google.com/open?id=1Hn...xYm0J7R02RU1L8

The spray volume i made like this

https://drive.google.com/open?id=1z0...QcEI17mRmFNCz_

https://drive.google.com/open?id=1Wf...UG-n70Q_ZQ0iLH

I will label 5 walls of the cube as outlet and one wall which is attached to the outlet will be designated as wall only. The inlet will be the top circular part of the atomizer.

Is this ok?

Thanks

[vinerm]

You do not require the atomizer model. All that's needed is a cubic or preferably a cylindrical domain (cylinder preferred because sprays are cylindrical). Fluent predicts atomization based on the data provided in the Injection and not based on the geometry of the injector; in a way, the effects of the geometry of the injector are included in the data provided. That's why these are called models.

If you want to simulate the physical injector, then you have to use VOF-DPM.

[Swish31]

Alright.
The mesh should be dynamic right?

[vinerm]

No, you don't need dynamic mesh. Just a plain cylinder or box will do. If there is air coming in along with water, then there should be air inlet at the same location you specify for injection.

[Swish31]

Ok i will try it out and revert back.
Thank you for helping me.

[Swish31]

If i model the cylinder, then where should i give the inlet in boundary conditions, do i need to create a small small opening or anything?