Tapered fluidized bed

MFiX
#1

hello.
I have some question about tapered bed:

  1. I want to simulate a tapered bed with 2 different kind of solids. can I use TFM solver for this purpose?
  2. How can I define static height (H0) in region?( I defined about 5 cm but didn’t show this size, it seemed be less than 10 cm)
    3.I have problem with DT and DT min. however I changed the meshes and maximum inlet velocity factor, it didn’t run.
    I will attach my purpose project and my simulation file. I don’t know where is its problem in running?
    spouted-bed-cone.2019.11.03.mfx (17.3 KB)
    tapered%20bed
    tapered%20bed690×914 110 KB
#2

First, your geometry doesn’t intersect the inlet and outlet boundaries. Either extend the geometry past ymin and ymax or keep the same geometry and adjust to say min=0 and ymax=0.24.

Second, The Initial Condition is not physical. Both solids phases are initialized with a volume fraction of 0.3, which corresponds to a void fraction of 0.4. This is below the max packing limit of 0.42 set in the TFM tab. Either lower the max packing value below 0.4 or increase the initial solids volume fraction to say 0.28.

#3

Thank you for your attention.I did this instructions and I could run it, and then as I don’t know haw I can use MFIX post processing, I took results to ParaView for post processing.
as you see in attached picture, I couldn’t see a clear result. I don’t know what I should do? Should I fine grids in Mesh sub pan or change the samples in sample implicit in Geometry settings?or do the other thing?

1
11911×1013 222 KB
14
141909×1021 202 KB

#4

What do you mean, looks like model output to me…

#5

I mean, whit this conditions that you told me and I applied them and succeeded to take a run, I can’t see a clear contour such as this contour that I have shown in a image in below. Actually I want to see phases void fraction, solid velocity, gas mean velocity and etc as clear as a contour which exists in the image that I attached in below .
Unfortunately in my tapered bed contours I can’t see them clearly. (I can only see some fine squares in tapered bed contour that I sent in the previous image.)
Indeed I want to have a contour with high resolution so I think it refers to my meshing size in MFIX.
Is it true?

contour
contour1909×1015 213 KB

#6

First, you should only open the VTK files (vtu, vtp, or better pvd files to get the time series). The .RES file is only suitable for rectangular geometry.

Second, cell data will always look pixelated. You will get more details with a finemesh (as shown in your rectangular geometry) than with a coarse mesh (tapered bed). If you can afford to run a 3D simulation with a fine mesh you will get a better resolution.

You can also use the “Cell data to Point data”, which will interpolate the cell value to each cell corner, and that gives a smoother data representation.

#7

Thanks, I got it.
So I created a new geometry with difference filter, instead of intersection filter. I applied all the things that needed. after that, this project is running, but its parameters don’t change while it is running.( all of the parameters are 0 after a few seconds of running started.)
I don’t know what is the problem. I attached my *.mfx file for you. would you mind help me please to find my fault?
new.sample26.11.1.mfx (15.4 KB)

#8

You only have one cell in the z-direction, so the mesher cannot resolve the geometry and you end up with zero computational cells (100% blocked cells):

GRID STATISTICS:
 NUMBER OF CELLS          =    18887
 NUMBER OF STANDARD CELLS =        0 (  0.00 % of Total)
 NUMBER OF CUT CELLS      =        0 (  0.00 % of Total)
 NUMBER OF BLOCKED CELLS  =    18887 (100.00 % of Total)
 CARTESIAN GRID PRE-PROCESSING COMPLETED IN     1.40 SECONDS.

You need to increase the number of cells in the z-direction.