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Useful LES tools in Fluent - Part 4

Posted March 7, 2014 at 03:59 by sbaffini (NuTBox)
Updated December 21, 2016 at 10:08 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...
Attached Files
File Type: c remap_par.c (14.4 KB, 724 views)
File Type: pdf remap.pdf (24.2 KB, 827 views)
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Useful LES tools in Fluent - Part 3

Posted October 21, 2013 at 08:06 by sbaffini (NuTBox)
Updated December 21, 2016 at 10:08 by sbaffini (Update)

These are the implementations of two static SGS models, due to Vreman and Nicoud (see the attached files for the detailed references). These models are in the same spirit of the well known WALE model; still, they are different in several aspects.

The models are provided without any kind of warranty; still, no specific problem came up during testing.

For wall bounded turbulent flows in Fluent i strongly suggest the Vreman model due to its specific, theoretically wrong, near...
Attached Files
File Type: c vreman.c (1.7 KB, 518 views)
File Type: c svd_sgsmut.c (2.3 KB, 346 views)
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Useful LES tools in Fluent - Part 2

Posted August 2, 2013 at 05:27 by sbaffini (NuTBox)
Updated December 21, 2016 at 10:09 by sbaffini

A couple of routines i regularly use to output solution files in more manageable ascii files for post-processing in MATLAB. Of course this only makes sense when working in simple geometries where cells have regular patterns (e.g., simple boxes for computations in channels and ducts).

1) output.c: Used to dump an instantaneous field file

2) outputavg.c: Used to dump an averaged field file

More details can be found in the files
Attached Files
File Type: c output.c (1.3 KB, 302 views)
File Type: c outputavg.c (2.7 KB, 764 views)
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Useful LES tools in Fluent - Part 1

Posted August 2, 2013 at 05:15 by sbaffini (NuTBox)
Updated December 21, 2016 at 10:09 by sbaffini

Here i collect some very basic tools i used when performing basic LES computations in Fluent.

1) Custom field function for the Q criterion (q_crit.txt, to be renamed in .scm). Some Fluent versions (12, 13 and maybe 14) only have a "Normalized Q criterion" scalar, while previous ones simply don't have it at all. This custom field function is what i used in those dark days.

2) Several initialization routines (init*.c and scalefield.c) fully described in the files...
Attached Files
File Type: txt q_crit.txt (2.3 KB, 2326 views)
File Type: c initialize_chan.c (1.7 KB, 724 views)
File Type: c initialize_pipe.c (1.6 KB, 577 views)
File Type: c initTGV.c (1.3 KB, 515 views)
File Type: c scalefield.c (787 Bytes, 589 views)
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Q-criterion isosurfaces in MATLAB

Posted July 1, 2013 at 12:33 by sbaffini (NuTBox)
Updated December 21, 2016 at 10:09 by sbaffini

Let us suppose you have the following matrices:

x(nx,ny,nz): x coordinates of your grid

y(nx,ny,nz): y coordinates of your grid

z(nx,ny,nz): z coordinates of your grid

dudx(nx,ny,nz): x-wise derivative of x-wise velocity component

dudy(nx,ny,nz): y-wise derivative of x-wise velocity component
.
.
.
dwdz(nx,ny,nz): z-wise derivative of z-wise velocity component

This is, more or less, how i would...
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