Different outcome between Micress 6.2 and 6.3

technical aspects of .dri file generation (e.g. debug mode ) etc...
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Junny
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Different outcome between Micress 6.2 and 6.3

Post by Junny » Thu Jan 19, 2017 1:45 pm

Dear Bernd,
I have just updated my Micress from Version 6.2 to 6.3 and tried with the same .driv file to compare the outcome. However, i noticed the difference in the phase morphology and fractions, see below the attached phase images. The phase mapped in red color is austenite, transformed from a pearlite. It can be seen that the simulated fraction of austenite with v6.3 is higher than v6.2. Also it appears that transformation kinetics of cementite is also faster with v6.3.
During the simulation, one extra requirement is needed in V6.3. It aks for an input of

#Please specify a criterion for the direction
# of the direction of the redistribution model:
# Options: local_velocity average_velocity bottom_temperature

I tried all the three separately and the phase outcome appears the same. Could you please be kind to explain a bit about the different between the two versions? Also what do the three options for the redistribution model mean?

Many thanks and kind regards
Jun
Attachments
v6.3.JPG
v6.3.JPG (32.93 KiB) Viewed 1546 times
v6.2.JPG
v6.2.JPG (30.25 KiB) Viewed 1546 times

Bernd
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Joined: Mon Jun 23, 2008 9:29 pm

Re: Different outcome between Micress 6.2 and 6.3

Post by Bernd » Thu Jan 19, 2017 11:31 pm

Dear Junny,

Different MICRESS versions always show numerical differences because we improve models, remove errors, and sometimes have to take decisions which change the numerical behaviour of MICRESS. Typically, the more stable an application is running and the more carefully the input parameters have been selected, the lower will be the impact of the specific version number.
However, if differences are so big as in your case, it indicates a conceptional problem. In your case it certainly is the way how you treat Mn in the simulation and how you have chosen the phase diagram data. It is hard to predict what happens when you choose nearly infinite slopes in both phases, and any change in the exact numerical implementation will correspondingly have a drastic effect...
In the implementation of the nple/para models, the behaviour of the phase transformation front depends its moving direction. The new option allows evaluating this direction either locally (in each interface cell), averaged per interface or by just getting it from the temperature trend. The latter is the most stable one, but is only useful if there is a clear temperature trend like in your case.

Bernd

Junny
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Re: Different outcome between Micress 6.2 and 6.3

Post by Junny » Fri Jan 20, 2017 9:14 am

Dear Bernd,

Many thanks for the kind explanation.

With kind regards,
Jun

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