Learning Forum

[Armand]

Hello

I have been doing the tutorials, called for Modeling Uniform Fluidization in 2D Fluidized Bed.

I did this at the beginning and it gives me a constant value equal to the bed's weight (no matter the velocity).

I just wondering if anyone had met the same problem, and what was the way to solve it? Please feel free to reach me via 

You answer will be appreciated.

Best Regard

 

[Armand]

the detailed date

[Rob]

Please post images of the bed, ie the mass fraction of phases. Which model are you using? 

[Armand]

Hi,

What I were doing is the content of the tutorial, and the tutorial is in the attached files.

 I used the multiphasic eulerian model

Best regards,

Armand

[Armand]

[Rob]

Which I am not allowed to open or download. Please post the images I asked for. 

[Amine Ben Hadj Ali]

What are now your questions? If you type fluent fluized bed tutorial words in Google you will find a Fluent tutorial on that. 

[Armand]

hi,

yes,I can find it, but  it gives me a constant value equal to the bed's weight (no matter the velocity).

Best regards,

Armand

 

[Amine Ben Hadj Ali]

You need to be much more precise in your communicaiton: what is the constant value? Are you talking about pressure drop? Perhaps you reached the minimum fluidization velocity?

The key feature in capturing bed height and pressure correctly is the spatial and temporal resolution of the simulations. Specifically, for spatial resolution, mesh size should be smaller than 10*dp (particle diameter) (delatx<10dp)

[Armand]

Even if the gas inlet speed is zero, the bed pressure drop is equal to the weight of the bed material.

Best regards,

Armand

[Armand]

In my project, the spatial resolution is what you say.

Best regards,

Armand

[Amine Ben Hadj Ali]

Perhaps reporting issue otherwise you won't get different profiles: remove the bed density from pressure via custom field function. I cannot now check what we have done years ago to get to get the well known curve.

[Amine Ben Hadj Ali]

How are u reporting pressure?

[Armand]

Is the meaning of your picture that you can get this curve by refining the grid?

Best regards,

Armand

 

[Amine Ben Hadj Ali]

Stop referring to old posts (my posts) and respond to the comments. For sure the walls have a sustaining effect and you need required resolurion but you can check if the hydro head is spoiling pressure field. We obtained good result for drop curve.

[Armand]

I reported the pressure drop by monitoring the total pressure of the air and the static pressure of the mixture.

Best regards,

 Armand

 

[Armand]

How can I check  if the hydro head is spoiling pressure field?

Best regards,

Armand

[Amine Ben Hadj Ali]

I looked back to my tutorial: I am just evaluating the static pressure  @inlet and @outlet (set as outflow). In the tutorial the min. fluid. velocity is about 8 cm/s. I will update later once again.

[Armand]

Thank you very much for your reply. Looking forward to your update.

Best regards,

Armand

[Amine Ben Hadj Ali]

So I run basically three points far below the expected 8 cm/s

[Amine Ben Hadj Ali]

and I definitely can confirm that the pressure difference is increasing.

[Armand]

Can you tell me in detail about the differences between your settings and the tutorial?

Best regards,

Armand

[Armand]

What you mean is that compared to the tutorial, just change the pressure outlet to outflow.

Best regards,

Armand

 

[Amine Ben Hadj Ali]

1 meter height 0.15 m bed width. I used wen drag and enabled Schaeffer friction and frictional pressure after Johnson. Time step size 0.0001 s. One has to be patient to reach steady state pressure level.

[Armand]

How long does it take to reach steady state?Which type of pressure do you monitor in import?

Thank you very much for your reply. Looking forward to your update.

Best regards,

Armand

[Amine Ben Hadj Ali]

Best to monitor pressure differences between in and out. Create two reports based on area average of pressure than a third one for difference and monitor that.