MAX_DT becomes A Very Large Number

Hi, everyone,

In my case, MAX_DT displayed in dashboard became a vary large number. Did you meet it before? Why is this? Does it mean that there is something wrong with my setting?

image

are you letting the dt get that big? There should be a limit.

Hi, Weber

DT is limited between 1e-3 to 1e-7.

By the way, sometimes, the estimated time remaining in my simulation also becomes a very large number. It is very strange.

The “estimated time remaining” is not an accurate number and fluctuates considerable as the time step changes. In the beginning when the solver is taking small time steps, expect the “estimated time remaining” to be large. As the simulation approaches a steady state, the “estimated time remaining” should be more reasonable.

Do you mean that MAX_DT and “estimated time remaining” , in fact, have nothing to do with the setting of simulation and they do not reflect whether the setting of case is correct or r not?

I still hope someone can give me a clear answer about these questions, i.e. why there are such large numbers displayed in dashboard as shown in my two posts.

There was a bug in the elapsed time display that was fixed in 20.2 (see bottom of MFiX 20.2 Release Announcement - Multiphase Flow Science Group at NETL). This may explain what you are seeing if your version is lower than 20.2. To get a better chance of having your questions answered, it is always good to provide details about the version and OS you are using (mfix.netl.doe.gov/doc/mfix/20.3.1/about.html#support-forum)

Thank you for your reminding me of how to make a batter post.
Here is the supplementary information.

mfix version: 20.2.1
OS: Ubuntu 16.04.7 LTS amd64 installed in VMware 12.0 in Windows7 system