Learning Forum

[mar1ne]

Good morning,

Thank you very much if you are reading my post. I am new to Fluent and I have difficulties with my discrete phase analysis.

I am using Fluent in order to see a particles powder flux function of the distance from an axis.

The problem I face is that I can see the DPM concentration (kg/m3)  function of the distance from this axis but there is no time dependance.

When I export with File> Export> Particle History Data> Ensight and open on a text file I see the DPM concentration datas delimited by part2, part5, part6, part8, part10. What does these parts and the numbers mean ?

There is no time indication in this file. How can I have the Powder flux (kg/m2/s) ?

I have a discrete phase with unsteady particle tracking. The particles are injected with gas. It might be a continous injection (I am not sure that I have computed it well, I put Start at 0 and Stop at 100s but when I watch the particle tracking I see space between the injections). The gas is the continous phase (it is steady and turbulent so I use Viscous k-epsilon method).

 

Thank you very much for having read my post and tried to help me !

Kind regards,

Marine 

[Rob]

What are you trying to find out?  

[DrAmine]

Please Add some screenshot if injection and DPM panel and tell us what you want to visualise.

[mar1ne]

Hello, 

Thank you for your interest,

I am trying to see the particles distribution in a plane after the injection. 

 

For now I have a 2D nozzle with a continuous gas phase and a discrete phase with my particles.

My discrete phase is unsteady with interactions with the continuous phase.

I inject the particles from a surface, in a continuous flow, that's why I have put stop at 1000s.

 

I would like to do something like that (from the article "Numerical simulation and experimental validation of powder flux distribution in coaxial laser cladding.") : 

I have exported my datas with File>Export>Solution data> ANSCII and by multiplying DPM by the velocity I have                                                                                                     

But to have that, I have needed to take the values for all the planes between 0.04975 and 0.05025 . If I take only the plane at 0.0500 m from my injection I only have two values. It is maybe because there is not enough particles injected or not continuously, but I have put the flow rate...                                                                                                                                                                                                                                 

I have spoken about time in my last post but I think that I will never have time information as I treat my continuous phase in a Steady way. I think it is not a problem as I just want to know in a specific plane, where my particles will probably be.

Best regards,                                 

Marine         

[Rob]

If you're running transient particles it's very possible that they've not got anywhere in your model: the oldest have only been in the system 0.006s! 

[DrAmine]

1/Why unsteady particle tracking? I guess steady streams being injected makes a sense here with the flow being steady-state

2/Post-Processing: Either you create a sample at the planes and then read the sampled data back into Fluent fgo to histogramm and get the mass flow of all particles and divide by the area. Or do all via UDF. Or do it by enabling mean values under DPM Panel: then you will get DPM Mean quantities which can be used to get a sort of mass flow. Divide then by area.

[mar1ne]

Thank you very much for your answers.

 

Rwoolhou, Yes they don't stay for a long time in my domain but it is not a problem beacause I whant to know if there are a lot of particles going through one point after my injection. I want to have a particle flow at one point. Do you suggest I should do a steady particle tracking ?

 

Abenhadj, I have used Unsteady beacause I wanted a continuous injection. With unsteady I can say the start and stop time of my injection while I can't in steady. Did I do a mistake ? Just to know, my continuous gas flow is turbulent.

When you say "Create a sample at the plane" do you mean create a new surface in graphics> Contours> New surface, and see on that surface ?

Was exporting like I did wrong ? 

I will try with histogramm, thank you.

[DrAmine]

In steady-state you will also a steady continuous injection.

With plane I really mean a plane and not an iso-surface. You can create that under Results. Perhaps you have already defined the planes where you need exporting already as interior so that you do not need to create anything just make a sampling there.