The prediction of pressure drop failed for Modeling Uniform Fluidization in 2D Fluidized Bed

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  • Last Post 12 October 2019
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Armand posted this 07 October 2019

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

 

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rwoolhou posted this 07 October 2019

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

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abenhadj posted this 10 October 2019

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.

Best regards,

Amine

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abenhadj posted this 11 October 2019

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

Best regards,

Amine

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  • Armand
abenhadj posted this 11 October 2019

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

Best regards,

Amine

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abenhadj posted this 11 October 2019

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.

Best regards,

Amine

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abenhadj posted this 12 October 2019

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.

Best regards,

Amine

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Armand posted this 07 October 2019

the detailed date

Armand posted this 07 October 2019

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 posted this 07 October 2019

rwoolhou posted this 08 October 2019

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

abenhadj posted this 10 October 2019

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

Best regards,

Amine

Armand posted this 10 October 2019

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

 

abenhadj posted this 10 October 2019

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)

Best regards,

Amine

Armand posted this 10 October 2019

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 posted this 10 October 2019

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

Best regards,

Armand

abenhadj posted this 10 October 2019

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.

Best regards,

Amine

abenhadj posted this 10 October 2019

How are u reporting pressure?

Best regards,

Amine

Armand posted this 10 October 2019

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

Best regards,

Armand

 

Armand posted this 10 October 2019

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

Best regards,

 Armand

 

Armand posted this 10 October 2019

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

Best regards,

Armand

abenhadj posted this 11 October 2019

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.

Best regards,

Amine

Armand posted this 11 October 2019

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

Best regards,

Armand

Armand posted this 11 October 2019

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

Best regards,

Armand

Armand posted this 11 October 2019

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

Best regards,

Armand

 

Armand posted this 11 October 2019

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

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