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Useful LES tools in Fluent - Part 4

Posted March 7, 2014 at 03:59 by sbaffini (NuTBox)

This is a routine to perform a remap of fields from an interior surface to an inlet surface during the computation. In practice this can be used to produce an LES inflow belonging to the class of the so called "precursor methods". Still, this is actually done in parallel with the main computation and not in advance.

The attached pdf file contains an explanatory image of the method while the .c routine should be sufficiently commented to be readily usable by anyone who actually...
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File Type: c remap_par.c (14.4 KB, 116 views)
File Type: pdf remap.pdf (24.2 KB, 126 views)
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Enosh, a structured grid generator (V)

Posted March 5, 2014 at 18:14 by lakeat (Daniel Wei's CFD Blog: (http://lakeat.co.nf/))

I have made significant improvement on the mesh export. The manual building up of OpenFOAM mesh now turns up really fast. I got a feeling that it could possibly beat even OpenFOAM's native blockMesh generator. In my test of a 3,200,000 mesh (for flow around a square cylinder). The building process took 90.51s in total. Here are more details:

...... [1] Done assembling the points. ( 7.09000s)
...... [2] Done assembling all cells & intnl cntrs. ( 40.62000s)
...
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Enosh, a structured grid generator (IV)

Posted March 4, 2014 at 12:20 by lakeat (Daniel Wei's CFD Blog: (http://lakeat.co.nf/))

Brief updates: I have succeeded optimizing some pieces of the code, from O(n^2) to O(n), but I still have another key module having the O(nlogn) complexity. It is unacceptable. I need to get rid of it.
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Enosh, a structured grid generator (III)

Posted February 28, 2014 at 16:21 by lakeat (Daniel Wei's CFD Blog: (http://lakeat.co.nf/))
Updated March 3, 2014 at 14:47 by lakeat (Clarification)

Updates:

Finally, I got the boundary file output working. Now it is able to export to the OpenFOAM mesh format. But I still need to do some optimization (hopefully to make it back to log-complexity with hash tables, thanks to c++11). Currently it takes too much time to build an OpenFOAM mesh manually.

Also I have tested the code on a clean ubuntu 64 environment with virtualbox, it seems to me anyone who wants to use it needs vtk and qt installed. Using synaptic package...
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Enosh, a structured grid generator (II)

Posted February 13, 2014 at 18:58 by lakeat (Daniel Wei's CFD Blog: (http://lakeat.co.nf/))

Spent four days in figuring out how to construct an OpenFOAM polyMesh manually, it is more complicated than I thought, the difficult part is how to construct a multi-block mesh. One of the annoying issues in a multi-block polymesh construction is how to handle its internal lines/surfaces, where two lines become one. And then the points indices and the face indices all have to change accordingly. There may be many approaches to address this, but I, after many days' thought, decided to use a brutal...
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