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PROBLEM: Nonlinear solver did not converge. Rotating Machinery

Posted 2011年11月24日 GMT-5 09:00 Fluid & Heat, Studies & Solvers Version 4.1 1 Reply

Jason Castro
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I am trying to simulate a stirring reactor, following the instructions of tutorial "Laminar Flow in a Baffled Stirred Mixer", but with some differences:
- The impeller is a turbine
- Viscosity of fluid is 0.038 Pa*s
- The angular speed is 68 rpm

My problem is that the solver did not converge, what could be happening?
The model is attached

Jason

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1 Reply Last Post 2016年11月28日 GMT-5 22:17
COMSOL Moderator

Hello Jason Castro

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DW
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Posted: 8 years ago 2016年11月28日 GMT-5 22:17
Hello,

This model will converge if you take these steps:
(1) Add boundary layer meshing to the rotor.
(2) Add boundary layer meshing to the interface of the rotating domain with the stationary domain.
(3) Add study 1 (frozen rotor study) before study 2 (time-dependent study).
(4) Converge the frozen rotor study using several values of rpm, ramping up the rpm e.g. 1, 2, 4, 8, 16, 32, 64, 68 rpm -- the desired value of rpm is 68 rev/min in the original model.
(5) Use the results of study 1 (frozen rotor) as initial conditions for study 2; to do this, go to "Values of Dependent Variables" in setup for Study 2 and set Settings: User controlled, Method: Solution, Study: Study 1 Frozen Rotor.
(6) Compute study 2 (time-dependent study).

-DW
Hello, This model will converge if you take these steps: (1) Add boundary layer meshing to the rotor. (2) Add boundary layer meshing to the interface of the rotating domain with the stationary domain. (3) Add study 1 (frozen rotor study) before study 2 (time-dependent study). (4) Converge the frozen rotor study using several values of rpm, ramping up the rpm e.g. 1, 2, 4, 8, 16, 32, 64, 68 rpm -- the desired value of rpm is 68 rev/min in the original model. (5) Use the results of study 1 (frozen rotor) as initial conditions for study 2; to do this, go to "Values of Dependent Variables" in setup for Study 2 and set Settings: User controlled, Method: Solution, Study: Study 1 Frozen Rotor. (6) Compute study 2 (time-dependent study). -DW

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