Gas boundary setting for time-dependent inlet velocity

MFiX How to
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#1

Hello developers,
I would like to build gas inlets whose velocity varies with time. In fact, I have checked the relevant methods in the forum and have implemented this in the TFM model (fluid_bed_tfm_2d2_2023-04-10T064256.958756.zip (738.3 KB)).
However, when I tried to implement this in the DEM simulation, I ran into a problem. According to the monitors at the two gas inlets and one gas outlet, the inlet velocity seems to be consistent with the setup(bc_v_g(1)=0+0.3* time; bc_v_g(2)=0+0.3* time), but the gas outlet velocity is much higher than the imposed inlet velocity.
In addition, the particle outlet range far exceeded the given particle outflow boundary range. This is very confusing to me. Could you please give some advice on this? Thank you very much!
Here is the DEM case file where the problem occurs.
fluid_bed_counterflow_2023-04-10T062731.442982.zip (144.7 KB)

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Fig. 1
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Fig. 2

#2

You have a chemical reaction that releases CO2 and that will increase the gas flow rate at the exit.

1 Like
#3

Thanks for your answer! This is indeed the problem, I checked the case and found that the initial temperature of the particles was set too high, causing a sharp gas release.