Newbie in Elmer

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campo
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Newbie in Elmer

Post by campo » 11 Mar 2016, 12:06

Hi everyone.

I´ve worked in CAE, mainly in mold plastic filling, and like it very much. Suddenly I´ve became interested in free software related to this because surfing internet I realized that it was much better than I thought. This way I met with Elmer and in my first look to Elmergui I fell in love with it :P .

Making tutorials I´m finding that it´s not so easy as it looked to do right but this has not discouraged me because I´m used to fight with this kind of things and somehow I like these difficulties. My own trial to walk alone without a tutorial support has been thermal air buoyancy. I´ve found that it´s not easy to get convergence with this kind of analysis but with the help of this forum I could get it.

It´s just an 293k air 200x200 mm cylinder with a 400K 20mm circular surface at the bottom and noslip at external surfaces. Look at the results in velocity_z,

Image



Great! Looking forward a more difficult one.
Attachments
buoyancy.png
buoyancy.png (67.52 KiB) Viewed 3548 times
Last edited by campo on 11 Mar 2016, 12:29, edited 3 times in total.

mzenker
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Re: Newbie in Elmer

Post by mzenker » 11 Mar 2016, 12:13

Hi,

I am curious to see your results, but cannot open the link - my company blocks it. If you reduce the image to 1024x768 or smaller and upload it here as attachment, it can be viewed inline directly by everybody... :)

Matthias

campo
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Re: Newbie in Elmer

Post by campo » 11 Mar 2016, 12:28

I´ve made an attachment as well

mzenker
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Re: Newbie in Elmer

Post by mzenker » 11 Mar 2016, 12:32

Looks good... :)

campo
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Re: Newbie in Elmer

Post by campo » 08 Apr 2016, 13:34

Hello, it´s me again.

In order to test my skill with Elmer and do a real test that I can afford to get results easily, this time it´s a vase with hot water cooling in air at ambient temperature. Again I have buoyancy but this time with two fluids.

Initial temperature in water is 330 ºK and in air 293ºK. The vase is made of plastic, so materials are air, water and polycarbonate. All boundaries are 0 in velocity and 293 ºK for the external walls of the cylinder that is the fluid mesh for the air. The plastic vase is 130 mm heigth and water 70 mm. The cylinder is 500 mm heigth.

These are the results for temperature an velocity (yellow is hotter).
300_seconds_temperature.png
300_seconds_temperature.png (55.38 KiB) Viewed 3477 times
300_seconds_velocity.png
300_seconds_velocity.png (78.3 KiB) Viewed 3477 times
While real temperature is 4 ºC lower than initial at 300 seconds the calculated is 5 ºC lower. A good result I think. The cooling is bigger in elmer because the height for the cylinder is not enough to get 0 in velocity, right?

What do you think?

Horizontal Company
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Re: Newbie in Elmer

Post by Horizontal Company » 11 Apr 2016, 20:11

Although this thread began on tutorials I decided the title would be perfect so rather than clutter the forum with a new thread I added my question to this one. If there is a better thread for me to post this in please tell me so.

I really appreciate the work programmers do and I notice that alot of the discussion centers around writing lines of code. While I can learn enough programming to change short sections of code I am not a programmer. I am a Machinist who needs to design, virtually test, and then generate G-code to build a part.

HERE IS AN EXAMPLE OF WHAT I NEED:

In original Mathcad you could draw an object and it would generate a formula for the part. I could manipulate the formula and it would change the shape and vice versa. I need to know what CAD programs load into Elmer. I would like engineering software to see stress on the part and aerodynamic flow around it in addition to heat and thermal transfer which may lead to a lowering of material strength which would be indicated in the engineering stress analysis of the part.

I am a machinist where do I look for tutorials on how to use, not program Elmer?


I'm a motorcyclist - Life's more fun horizontal!

mzenker
Posts: 1967
Joined: 07 Dec 2009, 11:49
Location: Germany

Re: Newbie in Elmer

Post by mzenker » 12 Apr 2016, 11:06

Hi,

Elmer does not really import CAD. To do that (and to prepare the mesh in general), you have to use additional software, e.g. gmsh or Salomé. Both import STEP and IGES format and can build a mesh. Elmer imports the output files, i.e. .msh format (gmsh) and .unv format (Salomé).

HTH,

Matthias

Horizontal Company
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Re: Newbie in Elmer

Post by Horizontal Company » 14 Apr 2016, 05:00

Thank-you very much! Do you know where the complete list of import/output formats is?


I just searched "format" finding 3 pages including this one dated 17 Dec 2015:

viewtopic.php?f=9&t=2023&p=14549&hilit= ... 5b1#p14549

From the external write-ups it looked like Elmer was ready to go but being built by people in their spare time it is expected to take many years. I may not be able to use this program but I will keep searching to learn about it.

mzenker
Posts: 1967
Joined: 07 Dec 2009, 11:49
Location: Germany

Re: Newbie in Elmer

Post by mzenker » 14 Apr 2016, 10:58

Hi,

besides this forum, there is documentation on Elmer here: https://www.csc.fi/web/elmer/documentation.
In the Elmergrid manual you will find a list of all formats imported by Elmer.

HTH,

Matthias

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