shear rate Dual domain mesh or 3D mesh, which should I trust?

[LeiteAndre]

Bom Dia
Estou fazendo uma comparação de resultados, entre dual domain e malha 3D.
O resultado da taxa de cisalhamento de domínio duplo está abaixo do limite da matéria-prima, enquanto o resultado da mistura 3D está bem acima do limite. Em qual resultado devo confiar quando na prática o material não está se degradando?

Good Morning
I'm doing a comparison of results, between dual domain and 3D mesh.
The dual domain shear rate result is below the raw material threshold while the 3D mixing result is well above the threshold. What result should I trust when in practice the material is not degrading?

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Traduzido por [@clacampos] através do Google Tradutor

 

[muthuraja.v]

Dear,

You can always rely with 3D results for better prediction, ( I hope you meshed it Feed system as 3D)

Please change DD results animation check timing at 100% filling then correlate with 3D mesh,

Best Regards,

Muthuraja

[StephaneCorduan1456]

You should not compare the shear rate bulk to the shear rate.

We have access to two different results of “shear rate” depending of the solver capabilities by:

The shear rate bulk is a “simple” result presenting the shear rate value as an average one. The shear rate bulk is quite comparable to the apparent wall shear rate calculation. 

This result is only possible only with the 2D solver

The shear rate results is the complete shear evolution by the velocity gradient through the cross-section (layer by layer).  

This result is possible with 2D and 3D solver.

The magnitude of the shear rate is higher than the shear rate bulk as it’s a complete distribution through the wall thickness and not anymore an averaged. The max. shear rate level is always located @ the wall interface (highest flow velocity gradient).

I've attached a picture comparing the shear @ gate for different models.

The shear rate evolution through the diameter is comparable for all the cases 2D Solver (BEAM), 3D Solver (BEAM), 3D Solver (TET)

[LeiteAndre]

Good Morning

So if the result Shear rate, maximum is above the value recommended by the raw material, can it be considered that I have to modify the gate?

even if it is already well dimensioned?

[LeiteAndre]

Good morning, one more question.

Which result can I consider OK in a 3D study?

[StephaneCorduan1456]

Yes absolutely. Nevertheless, for specific resin like POM or the resin sensitive to delaminate, I would recommend to minimize the shear rate level lower than the value specify by the resin supplier. The gate sizing is depending of the shear rate of course but also to the packing time efficiency (gate freezing for cold runner application or hot tip).

[LeiteAndre]

But which result can I use as a "best" reference?