Hello Everyone,
I am trying to reproduce the fluidized bed results from the paper "Hydrodynamic modelling of dense gas-fluidised beds: comparison and validation of 3D discrete particle and continuum models." However, I am facing some discrepancies when using cfdemSolverPiso in CFDEM.
Problem Description
- At 1.25×Umf and 1.5×Umf, the bed remains mostly fixed, whereas in the experiments, particles are already fluidized.
- At 2×Umf, particles start moving, but the average bed height is nearly half of what is reported in the publication.
I am using the same particle properties as mentioned in the reference paper.
Interestingly, another study ("CFD–DEM study of mixing and dispersion behaviors of solid phase in a bubbling fluidized bed") was able to reproduce the expected results using MFiX-DEM.
Details of My Setup
Solver: cfdemSolverPiso
Drag Model: KochHill
Time Step: 2e-6 (DEM), 5e-1(CFD)
Particle Properties:
variable rhop equal 2526
variable dp equal .0025
variable rp equal ${dp}/2
# matprops for Steel, stainless AISI 302 (http://www.engineeringtoolbox.com/young-modulus-d_417.html)
# type 1 particles, type 2 wall
fix m1 all property/global youngsModulus peratomtype 0.8e9 1.2e9
fix m2 all property/global poissonsRatio peratomtype 0.25 0.3
fix m3 all property/global coefficientRestitution peratomtypepair 2 .97 .97 .97 .90
fix m4 all property/global coefficientFriction peratomtypepair 2 .1 .1 .1 .20
fix m5 all property/global coefficientRollingFriction peratomtypepair 2 .06 .05 .05 .10
pair_style gran model hertz tangential history rolling_friction cdt
pair_coeff * *
Initial Packing: 25000 particle till height of 0.15m
1. Has anyone successfully replicated this case using CFDEM? If so, what settings worked for you?
Any recommendations on how to achieve better agreement with experimental results?
I would appreciate any insights or suggestions! If needed, I can share my simulation setup in more detail.
Regards,
Asif
carl | Tue, 04/01/2025 - 18:25
Fluidized bed
Hi,
I am having the exact same problem, I'm comparing my results to the Richardsson-Zaki equation and found that I get an exponent n almost exactly 1 too small. This means that something maybe Ksl is multiplied with the void fraction when it shouldn't. If I look in the manual https://www.cfdem.com/media/CFDEM/docu/CFDEMcoupling_Manual.html, it says Ksl is defined by being multiplied by the void fraction, but according to Zhou et al. https://doi.org/10.1017/S002211201000306X it shouldn't. However, I cannot find in the code where this void fraction is multiplied with Ksl.
Thank you.
carl | Tue, 04/01/2025 - 19:32
Fluidized bed
*The measured exponent n is 1 too large