# Particle reached maximum residence time

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February 9, 2016, 11:38
Particle reached maximum residence time
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Robin Cato
Join Date: Jan 2016
Posts: 5
Rep Power: 9
Hi everybody,

I am working on a separation cyclone with Lagrangian multi-phase.

I have problem with my Cyclone simulation.
I have simulated with particle size 1*10^-4, which I have to.
The problem is the particle circulates for a long time in the cyclone and reaches the maximum residence time (100 sec.) and the sub-steps are set to (1 000 000). I tried to set the residence time to 500 sec. but i get the same issue. I tried with a smaller particles ( 1*10^-5 ) and it works perfectly.

I have set boundary to Wall with Escape for the outlet in the bottom.

If anybody can help me to troubleshoot this issue I would appreciate it very much
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Last edited by Catostrof; February 9, 2016 at 11:48. Reason: Missing screenshot

 February 12, 2016, 08:34 #2 Member   Nils Join Date: Nov 2015 Posts: 59 Rep Power: 9 here you got an extract from another guidline When running steady state, the flow solver is not time stepping. In a single iteration, the Lagrangian solver is resolving the particle track from the particle entering to the particle exiting the domain. To generate a particle track, the Lagrangian solver has to substep with the particle trajectory and velocity to march out the path of the particle. In this way, Lagrangian substepping is analogous with time-stepping in unsteady models. The Lagrangian solver also knows from the particle velocity and track distance traversed how long the particle has been in residence, that is, the solution time that it has been in the domain. You can set a maximum residence time and/or a maximum number of substeps, after which it aborts the substepping and stop tracking the particle. In doing this, the solver does not continue to solve a track for a particle that never leaves the domain. Substepping occurs during a single steady state iteration. This is why it is only necessary to run the Lagrangian solver for a single iteration to generate the particle track - the Lagrangian substeps are internal to the solver iteration

 Tags cyclone separator, particle, residence time, sub-steps