Hello developers! I’m currently doing a simulation with 2d_TFM. It is found that the value of Zmax has a great influence on the simulation results after checking 2 Dimensional. I want to know how to set the zmax value properly. As shown in the figure below.
It should not have any influence on the solution. Can you please provide details about what you are observing.
Hello! As you can see in Figure 1, the temperature range of biomass obtained at Z=1m in the fluidized bed is shown. Figure 2 shows the simulated temperature range of biomass in the fluidized bed at Z=0.00052m. This has very big difference, hope can get your advice!
These snapshots are not shown at the same time. How do they both compare at time t=0.02s and time t=1.0s
I’m sorry I didn’t make a proper comparison last time. The following figure shows the biomass temperature range at 0.02s when Z=1m. (In the two attempts, the inlet temperature of biomass was set as 300K by boundary conditions). I hope you can give me some help, thank you!
OK thanks, please attach both models (.mfx and all udfs).
This is my case. Thank you very much. Waiting for your inspection and feedback!
copy_TFM.zip (29.8 MB)
Please also send the case with zmax=1.0. I want to run both cases exactly the way you set them up.
Here you are specifying a mass flow rate for the biomass inlet BC, so you cannot use the same value when zmax=1m and when zmax=0.00052m. The mass flow rate is converted to velocity based on the BC area, which will not be same if zmax changes. You have a lot more biomass coming in (per unit depth) when zmax=0.00052m compared with zmax=1.
If the mass flow rate was given to you (say from experiment), then you should use the same depth (zmax) as in the experiment.
If you used an inlet velocity instead of a mass flow rate, then the results would be the same
Please note that you get the following warning message. It is always a good idea to review all messages.
Warning 1100: Some volumetric or mass flow rates have been converted
velocity. Ensure that the third (unused) dimension in 2D simulations
is correctly specified (e.g., in axisymmetric cylindrical coordinates
ZLENGTH = 2*Pi)
Thank you very much for checking in on your busy schedule. I’m confused about Z =2 *pi. Is the Zmax value the diameter of the cylinder or the width of the feed port?
The 2*pi doesn’t apply to you since you are not using axisymmetric coordinates. This is just an example of a common error. Here your z_max is the regular z-direction extent.
Your reply was very useful. Thank you!