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Error : Failed to find consistent initial values
Posted May 31, 2016, 3:46 a.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD), Studies & Solvers, Structural Mechanics Version 5.0 1 Reply
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Hi,
I have made a 3D EHL model using Thin-Film Flow, Shell and Solid Mechanics.
When computing the model, the following error is popping:
"Failed to find consistent initial values"
Maybe this error is related to the initial conditions, but I inputted some initial values for Global Equations, so I cannot understand why COMSOL cannot calculate this model.
Following is the detailed info. about my model :
1. Solid Mechanics
Boundary Load is applied to the half side surface of the cylinder( F [N]). Its direction is to the inner of the cylinder.
Fixed Constraint is applied to the half surface of the cylinder, which is the others of the side surface functioned by Boundary Load)
2.Thin-Film Flow, Shell
A cylinder is rotating (its axis is penetrating through the centre of the upper surface and the bottom surface)
This physics is applied to the side surface and its thickness is b[m], where b is time-dependent and b is calculated by Global Equation: F-forcetot = 0( Initial Values: u(0) = b0(constant), ut(0)=b0/time where time is 0.001[s])
Here forcetot is the value of the surface integration. Pfilm is integrated by this over the all side surface of the cylinder.
If you cannot understand what I try to say, please ask me.
Sincerely,
Shinnosuke Kitayama
I have made a 3D EHL model using Thin-Film Flow, Shell and Solid Mechanics.
When computing the model, the following error is popping:
"Failed to find consistent initial values"
Maybe this error is related to the initial conditions, but I inputted some initial values for Global Equations, so I cannot understand why COMSOL cannot calculate this model.
Following is the detailed info. about my model :
1. Solid Mechanics
Boundary Load is applied to the half side surface of the cylinder( F [N]). Its direction is to the inner of the cylinder.
Fixed Constraint is applied to the half surface of the cylinder, which is the others of the side surface functioned by Boundary Load)
2.Thin-Film Flow, Shell
A cylinder is rotating (its axis is penetrating through the centre of the upper surface and the bottom surface)
This physics is applied to the side surface and its thickness is b[m], where b is time-dependent and b is calculated by Global Equation: F-forcetot = 0( Initial Values: u(0) = b0(constant), ut(0)=b0/time where time is 0.001[s])
Here forcetot is the value of the surface integration. Pfilm is integrated by this over the all side surface of the cylinder.
If you cannot understand what I try to say, please ask me.
Sincerely,
Shinnosuke Kitayama
1 Reply Last Post Jun 5, 2016, 1:09 p.m. EDT
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Posted:
8 years ago
Hi Shinnosuke
My knowledge about solid mechanics is limited, however, there are some general rules which may lead you to get an answer.
1) play with your mesh size. Sometimes coarser mesh converges, sometimes finer does. Then you can use finer mesh by using the solution as the initial condition.
2) Play with the forces that you apply. For instance, use only 10% of the current force. If you get an answer, use the solution as the initial condition for 0.2F and so forth.
3) Start your solution with a larger relative and absolute errors.
Do the above steps and let me know.
Amin,
My knowledge about solid mechanics is limited, however, there are some general rules which may lead you to get an answer.
1) play with your mesh size. Sometimes coarser mesh converges, sometimes finer does. Then you can use finer mesh by using the solution as the initial condition.
2) Play with the forces that you apply. For instance, use only 10% of the current force. If you get an answer, use the solution as the initial condition for 0.2F and so forth.
3) Start your solution with a larger relative and absolute errors.
Do the above steps and let me know.
Amin,