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How to use dynSmagorinsky model correctly ?

Posted July 9, 2014 at 18:47 by rkc.cfd
Tags sgs, turbulence

This is a good reference for why not to use upwind schemes for LES

Quote:
Originally Posted by alberto View Post
I think it is a tradeoff between stability and accuracy. In a finite volume code, your global accuracy is second order anyway. If you use higher order schemes for the convection term you can have some benefit, but you have also to evaluate how important this benefit compared to the standard linear scheme.

I'll try to give you some information of why central schemes are generally preferred in LES and then
...
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Old

TSAGI HERITAGE, NACA23012, M=0.6, alpha = 3 grad

Posted May 23, 2014 at 03:07 by skeptik (CFD notes)

Code:
#NACA 23012 exp. results alpha = 300' M=0.6
# Cp=(Pfoil - Pinfinity)/q; q = rho*U^2/2
#columns
#    x    Cp
#Upper
1    -0.200
2.5    -0.710    
5    -1.070
7.5    -1.270
10    -1.400
15    -1.345
20    -0.930
25    -0.795
30    -0.700
35    -0.610
40    -0.540
45    -0.475
50    -0.410
55    -0.350
60    -0.280
65    -0.220
70    -0.170
75    -0.130
80
...
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Old

TSAGI HERITAGE, NACA23012, M=0.642, alpha = 1.67 grad

Posted May 20, 2014 at 03:11 by skeptik (CFD notes)

Code:
#NACA 23012 exp. results alpha = 140' M=0.64
# Cp=(Pfoil - Pinfinity)/q; q = rho*U^2/2
#columns
#    x    Cp
#Upper
1    0.400
2.5    -0.380    
5    -0.780
7.5    -1.000
10    -1.160
15    -1.300
20    -0.925
25    -0.750
30    -0.640
35    -0.580
40    -0.520
45    -0.455
50    -0.395
55    -0.340
60    -0.280
65    -0.220
70    -0.165
75    -0.115
80
...
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Old

TSAGI HERITAGE, NACA23012, M=0.62, alpha = 0.17 grad

Posted May 16, 2014 at 01:34 by skeptik (CFD notes)

Code:
#NACA 23012 exp. results alpha = 010' M=0.62
# Cp=(Pfoil - Pinfinity)/q; q = rho*U^2/2
#columns
#    x    Cp
#Upper
0.648850002166  0.594351799714
1.00056308745  0.206219950622
3.45475808897  -0.457764109672
6.14544982025  -0.727560965045
8.6724130463  -0.885641269979
10.7411097154  -0.932091653311
13.3867544506  -0.89601940486
20.5760817776  -0.711551955646
24.6874864642  -0.627989777797
32.0344782778  -0.51406419197
...
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Old

TSAGI HERITAGE, NACA23012, M=0.5, alpha = -1.2 grad

Posted May 15, 2014 at 03:09 by skeptik (CFD notes)

I have some useful papers totally on Russian.

I will post some experimental results about airfoils here as i will translate it to appliciable form.

Here are the results which could be easily plotted by GNUplot. They are from far away 1946, TSAGI (Central Aero-, Gas-Dynamics Institute) publisher.

Code:
#NACA 23012 exp. results alpha = -112' M=0.5
# Cp=(Pfoil - Pinfinity)/q; q = rho*U^2/2
#columns
#    x, %    Cp
#Upper
1    0.6
...
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