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Useful LES tools in Fluent - Part 4

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Useful LES tools in Fluent - Part 4

Posted March 7, 2014 at 03:59 by sbaffini

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 knows what i'm talking about. If you don't, then you don't need it.

The routine only works in parallel (a serial version is available on request but its use is pointless in LES) and has been tested on straight circular and square ducts, both with structured and unstructured grids.

When compared with the default methods in Fluent (Vortex Method and Spectral Synthesizer) on the same number of cells, it is found to be around the 18% faster on average (different parallel partitions, load balances and hardware architectures). When the parallel partitioning is optimized the saving is higher.

A preliminary testing of the procedure has been presented here:

http://proceedings2012.caeconference...icoMilano.html

While additional details will be present in my forthcoming Ph.D. thesis, which i will share as soon as i will defend it.

The auxiliary flow is driven by a fixed source term (which nonetheless can be easily modified). An alternative version based on a PID controller to fix the mass flow rate and/or an additional integral parameter (say, the swirl number) is also available on request. However, this PID version has not been toroughly tested and some additional work might be needed.
Attached Files
File Type: c remap_par.c (14.4 KB, 125 views)
File Type: pdf remap.pdf (24.2 KB, 140 views)
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