[kaveh0a]

Hey guys,

I'm trying to inject particles with 100 m/s velocity into my computational domain using cone injection in the DPM model. Discrete phase interacting with the continuous phase and unsteady injection is performed. Deposition report is correct; however, when I plot velocity contour, there is no sign of cone injection. The particles enter the domain with high velocity and simulation is performed with two-way coupling, why there is no sign of cone injection in the velocity contour?

Kaveh

[vinerm]

Velocity contours are for continuous fluid and not for Lagrangian phase. For Lagrangian phase, you need to plot Particle Tracks.

[kaveh0a]

Thanks for your reply Vinerm,

I used particle tracks, and there is an injection but it is not like a cone.
I need a contour like the figure below:



any suggestion?

kaveh.

[vinerm]

How does contour for your case look like? By Particle Tracks I do not mean enabling of DPM model. Instead of plotting contours, plot Particle Tracks under Graphics.

[kaveh0a]

I used particle tracks under graphic options, and there was 3D figure of the injected particles. there were two problems:
1. near the injection point there were no particles
2. I need 2D velocity contour just like the figure that I sent

Thanks for your replies,
Kaveh

[vinerm]

After clicking Display in Particle Tracks, does Fluent show information about Tracked Particles and Escaped Particles? If Tracked particles are 0, then there is problem with the injection setup. If there are positive number of Tracked Particles and almost equal to Escaped, and those are not visible in the display, then most likely all of those are escaping from the inlet.

[kaveh0a]

deposition report is ok and there is no problem about the tracked particles. Any idea about the 2D velocity contour? In two-way coupling discrete phase with high velocity should change the flow field.

[vinerm]

What do you mean by 2D velocity contours? Is your case 2D or 3D? If the case is 2D, then just plot the velocity contour without selecting any boundary or surface in the list shown in Contour Plot panel. If it is 3D, then you have to create a surface passing through the middle of the domain. This is done using Surface option. Then, select this surface while plotting the Contour. Do note that this is not 2D velocity contour, only the surface is 2D.

[kaveh0a]

My domain is 3D, and I created a surface in the middle of the model. When I plot velocity contour using this plane there is no sign cone injection. As you can see, in the figure above the effect of injection is obvious in the velocity contours. Using particle tracks in the graphic options I can show the injection 3D, which is useless foe me.

[vinerm]

Firstly, you need to ensure that Interaction with Continuous Phase is enabled. Otherwise, you won't see any effect. Secondly, the extent of the effects of secondary phase, the particles, on the continuous phase depends on the mass loading. If mass loading is very low, then the effect will be small. To confirm if there is proper effect of particles on the continuous flow, plot contours of DPM sources. If the sources show non-zero values, then the effect is being taken into account; just the mass loading is low.

[kaveh0a]

Thanks Vinerm for your replies,

I am sure that interacting with continuous phase option is enabled. However, when I plot contours of discrete phase sources (DPM mass source), the values of the legend is zero!
How this is possible when particle tracks report is right, and it shows an injection?

[vinerm]

Mass source will be zero. Check momentum source values. Mass source is positive only if there is mass transfer from particles to continuous, which I suppose is not applicable to your case.

[kaveh0a]

No momentum source values are not zero and it is in the order of 10^-06 for x,y, and z.

[vinerm]

Then it is confirmed that the particles are affecting the continuous phase. If you think that the effect should be more, then that means you need to increase the mass flow rate of the particles. But do not increase it artificially. If you are already injecting the required mass of particles, then the results are already according to the injection rate and presumably correct.