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-   -   set BC for fluidized bed (http://www.cfd-online.com/Forums/fluent/95032-set-bc-fluidized-bed.html)

NAD December 2, 2011 22:05

set BC for fluidized bed
 
hi. i tried to make fluidized bed simulation 2D.the geometry is simple:a cylinder 2D with inlet and outlet. BC are defined as flow:
Inlet at the bed bottom is designated as Velocity Inlet boundary conditions for both the gas and solid phases. The boundary condition at the top of the bed is a pressure boundary fixed at a reference value (atmospheric).
Solids are free to leave if entrained and then return to the computational domain from the bottom inlet with a same mass flux.
how i can fix this in fluent??? i mean this condition ''Solids are free to leave if entrained and then return to the computational domain from the bottom inlet with a same mass flux.''
thanks

shk12345 December 2, 2011 23:52

Re
 
hi
nice question but i have no idea.
May be you can generate a udf for mass flow inlet in which the inlet mass flow can be computed from the mass flow from the outlet.Give the inlet mass flow of the solid same as the mas flowing out of the system.

Try it i hope that works.
SHK

sangramroy December 5, 2011 04:33

are you trying to simulate a circulating fluidized bed? If so, in 2D you have a mention a certain solid velocity at the inlet assuming that they are always constant .

NAD December 6, 2011 21:39

hi. shk, sangramory thanks for your reply.

shk, i will try UDF and let u know.

sangramory, yes I'm trying to simulate CFB. more exactly. the riser of CFB without the loop of return (i.e. cyclone, standpipe, feed device...) for this i need an adequate BC which can replace the loop of return.

prishor September 19, 2012 05:23

Hi,
I am doing my project in simulation of bubbling fluidized bed. i had made 2D geometry with meshes. Now the problem is that i have to include the bed material(sand) with initial bed height to the geometry before the simulation. Can anyone help me in this regard as I am new to FLUENT.

sangramroy September 19, 2012 11:28

You have to 'patch' the regoin where you would like to have sand. The steps are as follows:

1) Adpat->Region-> Options-Inside-> Shapes-Hex-> Input coordinates( specify the coordinates to mark the region where solid is present)->Mark

To check whether the region is correctly is marked, go to Manage-> select region -> Display.

A new windows pops up showing the region marked.

2) Initialize the system. Then follow:

Solve->Initialize->Patch-> Select solid phase-> select volume fraction under variable-> insert a value of volume fraction under 'value' -> select the region under 'Registers to patch'-> Patch.

Its done.

To check the correctness before starting the simulation, you can check the contour plots of solid volume fraction. Please remember, don't initialize again after patching.

prishor September 20, 2012 00:55

Thank you Sangram..thank you very much...its a valuable information for me...once again thannxx..

regards,
prishor

prishor September 20, 2012 01:09

Dear Sangram,
May I have your mail ID so that I can contact you for any clarifications.

Thanks and regards,

Prishor P K

prishor September 26, 2012 09:39

Can anyone help to get some tutorial about analysis of Fluidized Bed Gasifier in FLUENT..

Please help me as I am new to this area

rayolau September 28, 2012 03:24

Hi!
I need do a patch for create a sand bed. It`s posible utilice patch and injections?

Regards,
Laura

Ramin1985 March 8, 2016 03:56

a question
 
Quote:

Originally Posted by sangramroy (Post 382579)
You have to 'patch' the regoin where you would like to have sand. The steps are as follows:

1) Adpat->Region-> Options-Inside-> Shapes-Hex-> Input coordinates( specify the coordinates to mark the region where solid is present)->Mark

To check whether the region is correctly is marked, go to Manage-> select region -> Display.

A new windows pops up showing the region marked.

2) Initialize the system. Then follow:

Solve->Initialize->Patch-> Select solid phase-> select volume fraction under variable-> insert a value of volume fraction under 'value' -> select the region under 'Registers to patch'-> Patch.

Its done.

To check the correctness before starting the simulation, you can check the contour plots of solid volume fraction. Please remember, don't initialize again after patching.

following this order, the region where is patched by sand will be marked, but how about the solids that are intended to fluidized? I mean how can I specify the region above the sands involving the solids at the initial state?
I have patched the region for the sands and I ended up with such result:
u (inlet air): 0.3 m/s
bulk density of solids: 100 kg/m3
run time: 1s

does it mean that the sands are also fluidizing?

http://img.majidonline.com/pic/31841...n of solid.JPG


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