Error using HYS drag model

MFiX
#1

I am exploring the different drag models that might be useful for a fixed bed. I wanted to try to use the HYS model but, for some reason mfix does not recognize the the model and continues to try to use the model until the program crashes. Does anyone know why this is? Does the HYS model just not work? i have tried using it in both 19.3.1 and 20.1.2.

#2

Hi Kwasiaddo. Are you still seeing this problem? If so can you share your project file?
Thanks.

#3

Hi, i am still unable to use that drag model for any of my DEM simulations. I am able to use them for TFM simulations though. I have attacked the project file here Halloway_file.mfx (15.0 KB)

#4

I have encountered this problem as well in version 21.1.4. It seems to be due to the fact that the HYS model is not referenced in drag_gp_des. I have tried modifying it and apparently it works now, although I still need to check if the results make sense. Anyway, this appears to be a bug to fix in future releases.

#5

@kwasiaddo - I apologize for not following up on this. Our small team got a bit overwhelmed last year due to lockdown etc and there were a few bug reports like this one that we didn’t get time to properly deal with.

@fmarchelli - thanks for bringing this back up. Unfortunately this missed the window for the 21.2 release but I will try to get it into 21.2.1 or 21.3. Can you share the modified code?

– Charles

#6

Hi Charles, here is the modified code. I tried to make it similar to drag_gs but I’m definitely not an expert, so I may have made mistakes. However, apparently it works and gives very similar values compared to the other drag models. My modifications are noted in the code as “additions to use the HYS drag model”. Thanks!
Filippo
drag_gp_des.f (9.2 KB)

#7

Hi Filippo.

I asked my colleague Jeff Dietiker to review this proposed change, and his response was:

I don't think it is that straightforward to fix. The HYS drag model needs an average solids velocity which is not easy to compute with DEM.

For now, we’re going to disable HYS for the DEM model. If you have a complete implementation of HYS for DEM, including average velocity, we’d be interested to see it.

– Charles

#8

Hi Charles,

thanks for the update. Unfortunately I have no other code to share, I will let you know in case I try to do a full implementation of the model.
Filippo