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Old   July 14, 2011, 05:31
Default particle solver control problems
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Hi all.
I am trying to simulate the deposition of particles in a trapezoidal channel thas has initially "clean water". Besides the deposition of these particles i am interesting to see particles concentration profiles along the water column. In this context, i am using the lagrangian particle tracking approach implemented in cfx. I am adopting the following conditions (the most relevant)ne-way coupling, normal speed at inlet of 0.01 for the water and particles, i have specified 20000 particles at inlet and a mass flow rate of 0.0109445kg/s-1 and at the bottom i have defined the values of 0.3 and 0.6 for the perpendicular and paralell restitution coefficients respectively (i do not have experimental data for this coefficients). In what concerns the particle solver control settings i have defined the following conditions:max.tracking time=2000 and max.tracking distance=25(the channel has 8 meters of extension). However, at the end of the simulation i am receiving the following messagearticle fate diagnostics
entered domain=20000;
Exceeded time limit=19995;
Exceeded integration limit=5;

As you can see i do not have a detailed information of how many particles have left the domain, how many are collected at the walls, etc..Can anyone with more experience give me a hint on how to solve these messages of particle diagnostics and to have this detailed information?Regards
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Old   July 14, 2011, 08:13
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Glenn Horrocks
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Looks like the particles are just hanging around and not going anywhere. Are you sure buoyancy is correctly set up? Have you set the gravity vector?
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Old   July 14, 2011, 08:40
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Thanks Glenn for your comment.
Regarding your question:yes i have defined it. I am using the following "specifications":
water-continuos fluid;
particles-material particles with density of 2650 kg/m3;
morphology-particles transport solid;
buoyancy model-option buoyant with (0,-9.81,0)m^2/s and
buoyancy density reference = 997 kg/m3.

Any more suggestion?
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Old   July 14, 2011, 19:33
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The message is clear - almost all the particles are still hanging around at your 2000s cut off time. I would look at them in the post processor and try to find why they have not done anything. Are they moving but very slowly? Are they moving at all? Do you need to increase the cut off time?
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