CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM

turbulentDigitalFilterInlet input stress profile does not match generated profile

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 15, 2021, 09:01
Default turbulentDigitalFilterInlet input stress profile does not match generated profile
  #1
Member
 
Tom Lauriks
Join Date: Apr 2020
Posts: 34
Rep Power: 4
Tom Lauriks is on a distinguished road
Hello,

I'm using turbulentDigitalFilterInlet to generate turbulence for an LES of a boundary layer. The profile of the normal streamwise stress - <u'u'> - used as input data, doesn't result in the same profile being generated on the inlet by the application (the generated profile is almost zero everywhere). The other normal stresses are generated approximately correct. <u'w'> is also incorrect, but I think that this might be caused by the incorrect <u'u'> (based on a sensitivity analysis from the literature).

I've double checked, and the input profile of <u'u'> contains the correct values, so that is not the problem. Does anyone have any ideas about what the problem might be?

Some more information.

I divided my inlet in several sections along the height, so that I can apply different length scales in each section. My domain is 1 m high. I retrieved an estimate of an isotropic length scale from a RANS simulation. I divided the inlet in 8 sections and applied a length scale in each section, corresponding to the average length scale at the height of the section in the RANS. I've furthermore assumed that the RANS length scale is Lxu, and I've calculated the other length scales as fractions of Lxu.

The following is the specification of the boundary condition on one of the inlet sections:
Code:
    inlet1
    {
        type            turbulentDigitalFilterInlet;
        value           uniform (0 0 0);
        n               (7 75);//(nHeight nWidth)
        L               ($Lxu1 $Lxv1 $Lxw1 $Lyu1 $Lyv1 $Lyw1 $Lzu1 $Lzv1 $Lzw1);// (Lxu Lxv Lxw Lyu Lyv Lyw Lzu Lzv Lzw)
        fsm             1;
        Gaussian        0;
        Ubulk           3.787;
    }
The Reynolds stresses and the velocity profile are experimental values from a wind tunnel.

I've tried changing the profile of Lxu and <u'u'>. Changing Lxu didn't have an impact on the stresses. Increasing the profile of <u'u'> by a factor of 10 did have some effect close to the bottom wall, but higher up this has no effect.



Tom Lauriks is offline   Reply With Quote

Reply

Tags
inlet, les, profile, reynolds stress, turbulence

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Compute shear stress interFoam hsieh OpenFOAM Post-Processing 58 June 20, 2022 04:15
calcFvcGrad Nico A. OpenFOAM Post-Processing 26 April 7, 2022 10:19
SU2 inlet profile error dwstevens SU2 1 June 8, 2020 16:08
[OpenFOAM] Paraview 3.98 - errors when saving geometry file pajot ParaView 1 September 28, 2013 10:45
gmsh2ToFoam sarajags_89 OpenFOAM 0 November 24, 2009 22:50


All times are GMT -4. The time now is 20:21.