Learning Forum

[nilotpalc]

Hi all,

I have facing issues with reaching a steady state in a Fluent-Rocky coupled simulation. I will briefly describe my problem below.

I have a 90 degree bend (one inlet, one outlet) with air flowing in at 150 m/s. After reaching steady state in Fluent, I exported the fluid flow into Rocky, where in particles are injected through the inlet at a constant speed and mass flow rate using a circular surface sitting at the inlet. The injection period is larger than the time of simulation. Everthing about the simulation looked fine until I plotted the particle count and particle in count vs. simulation time. What I had expected was the particle count would reach a constant value after some time. However, it kept on decreasing. What's more surprising was the particle in count too kept on decreasing, suggesting the circular surface was holding some particles back, instead of releasing them at a constant frequency. The attached image shows this:

If I add the no. of particles entering the domain at each output interval (marked by red circles in the image), I get a number which is equal to the total no. of injected particles shown by the Rocky solver at the beginning of the simulation. This means the total no. of injected particles is correct, although the plane doesn't release the same no. of particles between each pair of output intervals.

I have seen some Rocky tutorials (e.g., Transfer Chute, Mixing Tee) where the particle count does reach a steady state. I couldn't figure out what went wrong in the 90 degree bend example and would like to hear your thoughts on this!

[Lucas Bertollo Baggio]

Hello Nilotpal,

 

Could you guarantee that every particle is being kept inside the Domain?

A domain boundary too close to the Particle Inlet could make particles leave the domain in case of these being injected with "negative" velocity in the inlet (due to turbulence, for example). 

 

Best regards, 

Lucas