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Old   November 17, 2013, 16:24
Default Help for Low Speed Analysis
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Yosheph Yang
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Hi Everyone,

I am a new user in SU2. I am trying to perform an analysis for ONERA M6 wing, which is given in the User Tutorial. I used mesh_ONERAM6_turb_hybrid_fine.su2 as the mesh file. I just modified the Mach number and Reynolds number from turb_ONERAM6.cfg. In the configuration file, I used low Mach number (M=0.05) and Re=6E05.

After doing 65 iteration, both CL and CD became negative.
Does it mean that I have to change something else in the default configuration file (turb_ONERAM6.cfg) for doing low speed analysis?
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Old   November 18, 2013, 00:21
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Anant Diwakar
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Hi Yang

The Mach number in your case is very low, hence you have to use
"Incompressible" option in SU2.

There are some testcases given. You can refer them.

Thanks
Anant
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Old   November 18, 2013, 05:33
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Yosheph Yang
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Quote:
Originally Posted by diwakaranant View Post
Hi Yang

The Mach number in your case is very low, hence you have to use
"Incompressible" option in SU2.

There are some testcases given. You can refer them.

Thanks
Anant
Hi Anant,

Thank you for the information. I added this line in my configuration file. INCOMPRESSIBLE_FORMULATION = YES and other incompressible properties necessary.
After doing that, my freestream pressure is automatically considered as zero even after defining my own freestream pressure. Will it affect my Cp, CL calculation?
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Old   November 19, 2013, 18:18
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Thomas D. Economon
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Hi guys,

Just wanted to chime in and remind you that there are slightly different way for initializing the free-stream conditions for the incompressible solver:

% -------------------- INCOMPRESSIBLE FREE-STREAM DEFINITION ------------------%
%
% Free-stream density (1.2886 Kg/m^3 (air), 998.2 Kg/m^3 (water))
FREESTREAM_DENSITY= 998.2
%
% Free-stream velocity (m/s)
FREESTREAM_VELOCITY= ( 5.0, 0.00, 0.00 )
%
% Free-stream viscosity (1.853E-5 Ns/m^2 (air), 0.798E-3 Ns/m^2 (water))
FREESTREAM_VISCOSITY= 1.002E-3

Just in case this helps,
Tom
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