Learning Forum

[Vicky]

Dear Sirs,

I am currently doing a simulation of a horizontal pipe using Rocky dem and fluent, I have done the workbench that Rocky suggests, but I still have doubts about the following, please I hope you can help me with this:

1) How can I select the correct coordinate axis for the particles to enter the horizontal pipe? So far I can't get them to enter.

2) Where can I put the particle time step size in the Rocky software?

 

 

Thank you for your help.

[Rob]

You set the particles in Inputs, the "inlet" is where they're released from. Look further down the tree. 

Particle time step is in Solver>Advanced. Unless you know why you want to change it I'd leave the options alone. 

 

[Vicky]

Hello Rob,

Thank you for your answer.

Let me ask another question please, why in Fluent do I have this kind of result? 'reversed flow on XXX Ffaces of pressure-outlet X'

Thank you again.

[Rob]

Because flow is entering the domain from the outlet. Plot some contours/vectors in Fluent to see what's happening. 

[Vicky]

Thank you, I found the error.

[Vicky]

Hello Rob, I have been able to simulate the workshop proposed by Rocky. However, when I started working on my own simulation, the same problem still appeared even when I made the modifications you indicated.
I am injecting more than 10,000 particles into the pipe.
Do you have any idea why does that look like an error?

My version of Rocky and Fluent is: 2022R2

[Rob]

That looks like it's running then fails. One issue I've seen is the HDF (h5) format that Fluent uses can corrupt given the number of files written. In Fluent, under File>Preferences change I/O to Legacy. Unfortunately you lose adaption register definitions and it's less computationally efficient but it's more stable. Note, HDF is great for "normal" use, it's the many hundred case & data files that are written for the coupling that can cause a problem. 

 

[Vicky]

Hello Rob, I did that before but kept the same problem. So all last week I  had again with the option that you indicated but after several iterations, this message has appeared again:
Do you think it is a software update issue?

[Rob]

Check disc space, and whether IT are playing games at 2am. Also check the Fluent results when it fails, hopefully you'll still have a case & data to see if it's diverged.