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Old   January 3, 2015, 22:24
Question Divergence using Dynamic Mesh
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Renato Venturatto Junior
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Hello people!

Need your help!

I'm running a case of a simple cylinder with water flowing around it.

I wanna see the movement of the body due the forces acting on it.For this, I'm using an UDF to integrate the differencial equation of motion numerically (Fy=May+Cvy+Ky) and obtain aceleration(ay),velocity(vy),and position(y).

The problem occurs when I hook the following UDF to: Dynamic Mesh - Dynamic Mesh Zones - Rigid Body-Motion UDF Profile:

DEFINE_CG_MOTION(y_motion,dt,vel,omega,time,dtime)
{
vel[0]=0.0;
vel[1]=vybody;
vel[2]=0.0;
}

Problem:

# Divergence detected in AMG solver: pressure coupled -> Decreasing coarsening group size!
# Divergence detected in AMG solver: pressure coupled -> Increasing relaxation sweeps!

Error: Divergence detected in AMG solver: pressure coupled

Error: Divergence detected in AMG solver: pressure coupled
Error Object: #f

My question:Is there anything I need to set for the adjacent cell zone (fluid) or in the Dynamic Mesh panel in order to avoid divergence?

If you need further details about the settings of my case, please let me know.

Thanks in advance!
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Old   January 5, 2015, 19:26
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Renato Venturatto Junior
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Just for information, I'm getting the following error:

reversed flow in 23 faces on outflow 4.
# Divergence detected in AMG solver: pressure coupled -> Decreasing coarsening group size!
# Divergence detected in AMG solver: pressure coupled -> Increasing relaxation sweeps!

Error: Divergence detected in AMG solver: pressure coupled

Error: Divergence detected in AMG solver: pressure coupled
Error Object: #f

And the same happens for pressure-outlet:

reversed flow in 23 faces on pressure-outlet 4.
# Divergence detected in AMG solver: pressure coupled -> Decreasing coarsening group size!
# Divergence detected in AMG solver: pressure coupled -> Increasing relaxation sweeps!

Error: Divergence detected in AMG solver: pressure coupled

Error: Divergence detected in AMG solver: pressure coupled
Error Object: #f

I didn't say before, but I'm using ANSYS Fluent 15.0

Any ideias?
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dynamic mesh zones, dynamic meshing, udf and programming

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