[ray_lo]

Dear all,

Thanks for reading this. I've got this wierd thing about the continuity of a FLUENT cas.

I was using FLUENT 17.0 (on a workstation with Linux system) to calculate a turbulent jet flow using LES with NITA Scheme. I saved the cas and dat at time step 10000 when the continuity residual was about 0.005 and the case run steadily. After a while, I reloaded the cas and dat on the same computer and the same FLUENT without changing any setting of the cas and dat. Then the wierd thing happened that the continuity residual increase to 1.0 abruptly, and about 5000 time steps later, it rose to about 10.0 and the cas diverged.

I did NOT change the setting of the cas and dat at all, and used the same computer and same software.Why the continuity residual increase after reloading? Is there anyone know how to solve this problem?

Thanks a lot for your help.

[LuckyTran]

The case diverged, it's that simple.

[ray_lo]

Originally Posted by LuckyTran

The case diverged, it's that simple.

Hey, thanks your reply.

The thing is it seems not that simple. Actually, I first run the cas for 10000 time steps and saved the cas and dat every 500 time step. During this calculation, the residual kept steadily at about 0.005. Then I ended the Fluent at time step 10000, and reloaded the cas and dat I saved before, and restarted calculation without change anything. The strange thing is that no matter which dat I reload (even data at timestep=5000), the residual rises abruptly. Normally, should it be the same as the first calculation?

So I am wondering what makes the residual increase? Because at the first calculation, it runs well. Once reload the cas and dat, it increase. For now, this thing only happens when the LES + NITA scheme is used, would this is responsible for?

[LuckyTran]

I don't know why the residual is being reset for your case but...


The continuity residual is a scaled residual. If it is reset, it will be 1.


You're using a NITA scheme which has no outer iterations where the continuity residual has no meaning anyway.


Regardless of what the residual even is, divergence is not caused by residuals but by actual problems in case.

[Weiqiang Liu]

Hi,

I met the same problem. After I reload case and file, residuals and results just change very abruptly. I can't figure out why. Have you solved the problem?

Best