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-   -   error in polyflow while inverse extruding (http://www.cfd-online.com/Forums/fluent/48777-error-polyflow-while-inverse-extruding.html)

 shyam chunduru July 14, 2008 23:01

error in polyflow while inverse extruding

hello

i am shyam ,i had been trying to simulate inverse extrusion in the polyflow software.

i need to use Carreau-Yasuda law.

i am just trying with rectangle block of 0.02m,0.002m i had done with constant viscosity and had got the results. but i was unable to do this with varying viscosity and temperatures.

the following is the error i am getting.

["

***************************

* Expert tool diagnostics *

***************************

Out of convergence disk

***************************

* Expert tool diagnostics *

***************************

The problem F.E.M. Task 1 has not converged.

***************************

* Expert tool Suggestions *

***************************

There is a non-linearity in problem Inflow introduced by the power

law index (n) of the viscosity law. The value of the power law index

is 0.32.

The expert system suggests to use a Picard iterative scheme with a

number of iterations about 30 or 40.

There is a non-linearity in problem Navier-Stokes 3D introduced by

the power law index (n) of the viscosity law. The value of the power

law index is 0.32.

The expert system suggests to use a Picard iterative scheme with a

number of iterations about 30 or 40.

There is a non-linearity in problem Navier-Stokes 3D introduced by

the power law index (n) of the viscosity law. The value of the power

law index is 0.32.

The expert system suggests to use an evolution for this parameter

coupling with Newton-Raphson iterative scheme. The evolution scheme

must be the following :

- f(s) = 1/s

- S-ini = n = 0.32

- S-final = 1.0

- Initial increment = 0.4 = n/0.8.

If you can not define the evolution with those typical values of the

check the setup of your simulations.

************************************************** ********

* Expert tool advice in order to optimize the simulation *

************************************************** ********

At least one bad element has been detected in the mesh.

The worst has the following feature(s)

Negative Jacobian in element 3150, (x,y,z) = (0.0023884, 0.0009407,

0.06459).

Too small angle in element 2130, (x,y,z) = (0.0022212, 0.0009455,

0.04797).

Too big angle in element 2219, (x,y,z) = (0.0022555, 0.0009965,

0.04307).

Non-convex element 26, (x,y,z) = (0.019045, 0.0010259, 0.07519).

This can lead to local inaccuracies and possibly convergence

difficulties. It is strongly recommended to fix the mesh.

"]

In order to solve this i had tried by changing the mesh. some times second sugestion doesnt appear.

can any one give me sugestions to solve this problem.

thanking you

shyam

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