Non-negative cell detected by fluent after restarting an FSI problem

mahdi_rmahdi_r Member Posts: 1

Dear all,

I tried to simulate a discharging pipe in a tank with a velocity higher than flutter speed, which causes the pipe to oscillate in the tank. I ran this problem for 2s without problem but when I tried to restart the case at for example 1.9 s with the same time-step (I set the restarting point for fluent and Ansys mechanical exactly at 1.9 s), I got a "(DP 0) Update-Dynamic-Mesh failed. Negative cell volume detected." error.

I appreciate it if someone can help me


  • SteveSteve Posts: 152Forum Coordinator

    Hi @mahdi_r ,

    What changes were made to the setup before the restart? Please be specific and include screenshots.


  • mahdi_rmahdi_r Posts: 2Member

    Hello @Steve ,

    Thanks for the reply,

    I tried to replicate the error but I got a different error this time.

    What I do is save the file when the simulation finishes (for backup), and then save the file again somewhere else to continue the simulation. So for the last time ( when I asked the question) and this time (today) I used the same backup file (save it somewhere new so nothing happens to the backup file) and did the same procedure but this time I got this new error.

    This is what I did. I ran this simulation for 2 [s] with a time step of 0.01 [s] a week ago. It worked fine. then I wanted to continue the simulation, so today I changed the End time in system coupling to 2.1 [s]. and I get this error

    So, I tried to run restart it from 1.92 [s], so I first went to the setup part in the transient module and change the restarting time-step to 1.92 [s] (following image)

    then closed the Ansys mechanical and updated the setup, For the next step I open the solution part of the Fluent module and change the solution file to 1.9[s], and read it.

    then closed the fluent and opened the coupling module. Changed the coupling initialization to 1.9 [s].

    and then update the coupling and get this error (couldn't find Rnnn file).

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