#1 2021-12-14 11:00:11

mu

Member

Registered: 2021-12-03

Posts: 32

[SOLVED] A big difference in simulation result between SW and Salome

Hi,

We've conducted a transient thermal analysis using Salome and repeated the same with Solidworks for comparison. As you can see from the outcome below, both achieve thermal equilibrium of 29.xxx, however Salome took about 227s, while Solidworks took alot longer at 668s.

Question:

• What might have caused the two to take such a big difference in time?

• Is there a good way to determine which is "more accurate"?

model:

results:

Last edited by mu (2021-12-17 04:13:42)

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mu

Member

Registered: 2021-12-03

Posts: 32

Re: [SOLVED] A big difference in simulation result between SW and Salome

Same geometry were used, checked that the units are the same too

• Same material, with heat flux density

• Mesh fineness at salome

• Mesh fineness at SolidWorks is default config

Last edited by mu (2021-12-14 11:11:50)

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mu

Member

Registered: 2021-12-03

Posts: 32

Re: [SOLVED] A big difference in simulation result between SW and Salome

model

Last edited by mu (2021-12-14 11:16:13)

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mu

Member

Registered: 2021-12-03

Posts: 32

Re: [SOLVED] A big difference in simulation result between SW and Salome

heat conduction between three solids and no external heat flux , no heat source

model conditions as below：

Last edited by mu (2021-12-14 11:32:08)

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Volker

Member

From: Chemnitz

Registered: 2016-05-23

Posts: 92

Re: [SOLVED] A big difference in simulation result between SW and Salome

Is there an analytical way to obtain the function of thermal balancing?
Or other Question: which material property can you change to suppress geometrical nonlinearities as best as possible?

mu

Member

Registered: 2021-12-03

Posts: 32

Re: [SOLVED] A big difference in simulation result between SW and Salome

Laplace's equation

Two materials:
AL7075 = DEFI_MATERIAU(
  THER=_F(LAMBDA=130.0, RHO_CP=2700000.0)
)
Sliver = DEFI_MATERIAU(
  THER=_F(LAMBDA=420.0, RHO_CP=2530000.0)
)

Is there an analytical way to obtain the function of thermal balancing?
Or other Question: which material property can you change to suppress geometrical nonlinearities as best as possible?

Last edited by mu (2021-12-17 04:11:47)

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Volker

Member

From: Chemnitz

Registered: 2016-05-23

Posts: 92

Re: [SOLVED] A big difference in simulation result between SW and Salome

My question is: is there an analytical way to determine the function, see appendix. If we have this function then we can say clearly what is right and what is wrong.

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RichardS

Member

From: Munich, Germany

Registered: 2010-09-28

Posts: 563

Website

Re: [SOLVED] A big difference in simulation result between SW and Salome

Hi,
are you sure about your units?
In the mesh screenshot you say "mm", so I suppose thats the lenght unit you are using.
But in a later post where you have your material properties shown, it looks like SI units, with lenght unit "m".

Can you confirm which unit system are you using?

Best,
Richard

---

Richard Szoeke-Schuller
Product Management
www.simscale.com
We are hiring! https://www.simscale.com/jobs/

mu

Member

Registered: 2021-12-03

Posts: 32

Re: [SOLVED] A big difference in simulation result between SW and Salome

Hi, Volker

Our model do not have analytical solution.

My question is: is there an analytical way to determine the function, see appendix. If we have this function then we can say clearly what is right and what is wrong.

mu

Member

Registered: 2021-12-03

Posts: 32

Re: [SOLVED] A big difference in simulation result between SW and Salome

Hi, RichardS

I config the length units in study propertites

Which material property looks like SI units?  I don't understand the Material subject.

Hi,
are you sure about your units?
In the mesh screenshot you say "mm", so I suppose thats the lenght unit you are using.
But in a later post where you have your material properties shown, it looks like SI units, with lenght unit "m".

Can you confirm which unit system are you using?

Best,
Richard

Last edited by mu (2021-12-15 10:37:30)

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Volker

Member

From: Chemnitz

Registered: 2016-05-23

Posts: 92

Re: [SOLVED] A big difference in simulation result between SW and Salome

Your sure there is not an exponential solution to base e?

mf

Member

Registered: 2019-06-18

Posts: 391

Re: [SOLVED] A big difference in simulation result between SW and Salome

Hello,

Volker is probably right, your material parameters are most likely not correct. Your E is supposedly in N/m² RHO is in kg/m³, RHO_CP is also in SI units (the N-mm system value is much lower, see link to other post below), but your model is in mm. Only LAMBDA can be converted 1:1 (because W/mK is equal to mW/mmK)

Just like in https:__//www.code-aster.org/forum2/viewtopic.php?id=26082 you should correct your material parameters to the N-mm system, if you don't want to scale your model to meters.

Mario.

EDIT: if you corrected the material parameters and you also choose the same timestep in both versions, then they should be comparable. The results will be very much alike.

Last edited by mf (2021-12-15 12:35:24)

mf

Member

Registered: 2019-06-18

Posts: 391

Re: [SOLVED] A big difference in simulation result between SW and Salome

This pdf helped me a lot, regarding consistent units,

Mario.

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Volker

Member

From: Chemnitz

Registered: 2016-05-23

Posts: 92

Re: [SOLVED] A big difference in simulation result between SW and Salome

Now I remembered the exact technical term: its a "solid" calorimeter.
Now its should be clear how to calculate by hand

Last edited by Volker (2021-12-15 17:29:37)

mu

Member

Registered: 2021-12-03

Posts: 32

Re: [SOLVED] A big difference in simulation result between SW and Salome

Thanks for all the help!

I solved this problem by importing the stp file which is exported from Salome into SolidWorks and change the units of SolidWorks from Custom(MM, G, S) to MKS(M, KG, S).

Last edited by mu (2021-12-17 04:10:42)

mu

Member

Registered: 2021-12-03

Posts: 32

Re: [SOLVED] A big difference in simulation result between SW and Salome

Hi, Mario

Thanks for your help,  the results are very much alike just like you said.

This pdf helped me a lot, regarding consistent units,

Mario.

Last edited by mu (2021-12-17 04:08:22)

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mu

Member

Registered: 2021-12-03

Posts: 32

Re: [SOLVED] A big difference in simulation result between SW and Salome

the .comm file

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