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Old   March 22, 2015, 16:42
Default EngineMesh utilitities
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Hello,

I'm new in Open FOAM software (just after one basic online course). I'm interested in I.C. engines simulations. Do you know how I can get explanations (tutorials, descriptions) about engine utilities in Open FOAM? Specially:
- "MoveEngineMesh". I want to know how to prepare walls in "blockMeshdict" file (or in other utility to prepare mesh if it is better for engines) and files "MeshModifiers" , "DynamicMeshDict"
- Also what is necessary to run "engineFoam" solver (files in "0" and "system" folders).

My purpose is to run simulation for case of my master thesis (I did it already in AVL FIRE software which license I borrow for thesis preparation period). Below I present you link to presentation of my thesis:

http://prezi.com/dmif50zywkzl/?utm_c...py&rc=ex0share

Do you think it will be difficult to run in Open FOAM software ?
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Old   March 23, 2015, 14:04
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Have a look at the engineFoam tutorial case ($FOAM_TUTORIALS/combustion/engineFoam). For multispecies diffusion flames, you may need to go to sprayEngineFoam.

The main thing with the current existing engine mesh types is to have the proper patches (cylinderHead, liner and piston) and the right values in the constant/engineGeometry dictionary. You can use moveEngineMesh to determine if the mesh quality will be acceptable during the stroke. I suspect you will need to remesh periodically to keep aspect ratio of the cells at a good quality.
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Old   April 1, 2015, 15:37
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Thank you Marco for your response. It really helps me to start. I did not answer for a while because using OpenFoam takes me long time.

- About using sprayEngineFoam for multispecies diffusion: I didn’t activate multispecies module in

AVL FIRE because homogeneous mixture of methane was used, so I’ve just wanted to simulate

combustion. In the following link you can see movies how it looks:

https://www.dropbox.com/sh/w62sss9wm...5AyofEwIa?dl=0

- About tutorial which you recommend me ($FOAM_TUTORIALS/combustion/engineFoam) : this is kiva test tutorial and I cannot find the executive files for mesh. I’m using “simple

engine” tutorial which I found at following site:
http://powerlab.fsb.hr/ped/kturbo/Op...neTutorial.tgz

Now I stuck in following steps:

1. I don’t know which command I can use to execute the mesh (I tried “moveEngineMesh”, “moveDynamicMesh”, “moveMesh”. Do you know how to execute this mesh?

2. If I good understood I must only assign “cylinderHead”, “liner” and “piston” patches. I have to deactivate all valves settings. Do you know how?

3. Maybe you have access to more suitable tutorial?

4. About mesh: I prepare this with blockMesh utilities. I did “mergePatchpairs” but mesh is

complicated in joint area. In link below you can see result:
https://www.dropbox.com/sh/xxwfbp7ye...QHYf1oaIa?dl=0

In OF 2.3.0 one error appears in “checkMesh”:
https://www.dropbox.com/s/rnbq4yegp7...checkmesh?dl=0
Using OF ex 3.1 2 is not possible to execute “mergePatchpairs” tool (it is of interest for me).

5. Do you know how to manipulate mesh:

- Is it better to re-mesh periodically or make layer removal during stroke
movement? How to execute one of these methods?

- how to prepare sliding interface ?

I look forward to hearing from you.

Best regards

Gregory
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Old   April 1, 2015, 17:50
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1. The foam engine tutorial isn't completely straightforward. If you look at the Allrun script you will see how the mesh is initialized (converted from KIVA file) and then the application engineFoam is run (its being fancy and getting the application name from the controlDict).

moveEngineMesh and similar only move the mesh to see if your mesh motions are working properly.

2. engineMesh will work fine with additional patches beyond cylinderHead, liner and piston, but only the liner and piston patches will be moved; everything else will stay stationary, unless you are using fvMotionSolverEngineMesh

3. The kivaTest is very straightforward once you look at the Allrun script

4. Before using mergePatchPairs, make sure the mesh is acceptable without merging. I've found merging only works for the very simplest cases and you are usually better off ensuring your blocks are co-located.

5. When compressing, layer removal works well and shortens your runtime. On expansion you are better off remeshing.
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