Particles OUT and DT adjustment

Hi, can you help me to reduce the number of particle out and solve the DT adjustment. I encountered these warnings while rendering the 3d flow inside the rectangular box. The particle out reached almost 20% of the total particles in. May I asked when does particle out? Here's the warning i received.

Particles new: 2990 (total new: 116610) - Current np: 144747

Part_0266   2.660121     8258    35  1621.86 15-07-2023 14:33:13 

Particles out: 824 (total out: 19775) - Current np: 143923


*** WARNING: 10000 DTs adjusted to DtMin (t:2.76202, nstep:8611)


  • "Particles out" should not be a problem here if you are using outlet condition.

    In any case, I would suggest you to check the value of speed of sound. Is that value defined by you or computed by GenCase? You can see the value used in your simulations checking the content of Case.out (from GenCase). That value can be better defined if needed

  • The just created the value of speed of sound. I just copy the value on the xml file of flow cylinder.

  • The originally, the speed of sound is zero however I encountered an error about zero value of B value. This is because I set the g (acceleration due to gravity to zero). So I copy the value of speed of sound from the flowcylinder case (which is 15). The value of B is 41.000 (something). Do you think i should set the speed of sound close to zero?

  • Hi, I change the speed of sound from 15 to 1. Here are the warnings from the rendering in command prompt:

    1. Inlet/outlet 1: Velocity limits are unknown and RefillingMode==SimpleFull/SimpleZsurf is invalid for reverse flows.

    2. Inlet/outlet 1: VelocityMode==Extrapolated is not recommended for inlet (or reverse) flows.

    3. 1 DTs adjusted to DtMin (t:0, nstep:0)

    4. 10 DTs adjusted to DtMin (t:0.0995929, nstep:4)

    5. More than 1% of current fluid particles were excluded in one PART (t:0.281458, nstep:45)

    6. 100 DTs adjusted to DtMin (t:0.294449, nstep:49)

    7. More than 10% of particles were excluded (t:0.723131, nstep:147)

    8. 1000 DTs adjusted to DtMin (t:2.24301, nstep:499)

    9. More than 20% of particles were excluded (t:2.99212, nstep:671)

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