Re: choice of nterup and dtref
Posted: Thu Sep 05, 2019 3:09 pm
Hello,
Here is an update on a test on our cylinder test case:
simplec: Strouhal 0.17237, drag average 1.203, lift coefficient max 0.40941
nterup=2: Strouhal 0.18491, drag average 1.171, lift coefficient max 0.29611
nterup=5: Strouhal 0.18583, drag average 1.1684, lift coefficient max 0.28849
Where references from different sources (Jordan & Fromm, Smith & Brebbia, Scoanson & Spalding, Martinez, Gresho, Boisson) place the Strouhal number between 0.160 and 0.174, drag average between 1,02 and 1,43, and lift max between 0,2 and 0,30 and experiments (Tritton, Roshko) place the Strouhal number between 0.157 and 0.167 and drag average between 0,944 and 1,33.
So there is an influence of the nterup value, with apparent convergence when nterup is increased, but on such a sensitive test case, it is difficult for me to say which is "better", though the max lift fits better with references using nterup >= 2.
Best regards,
Yvan
Here is an update on a test on our cylinder test case:
simplec: Strouhal 0.17237, drag average 1.203, lift coefficient max 0.40941
nterup=2: Strouhal 0.18491, drag average 1.171, lift coefficient max 0.29611
nterup=5: Strouhal 0.18583, drag average 1.1684, lift coefficient max 0.28849
Where references from different sources (Jordan & Fromm, Smith & Brebbia, Scoanson & Spalding, Martinez, Gresho, Boisson) place the Strouhal number between 0.160 and 0.174, drag average between 1,02 and 1,43, and lift max between 0,2 and 0,30 and experiments (Tritton, Roshko) place the Strouhal number between 0.157 and 0.167 and drag average between 0,944 and 1,33.
So there is an influence of the nterup value, with apparent convergence when nterup is increased, but on such a sensitive test case, it is difficult for me to say which is "better", though the max lift fits better with references using nterup >= 2.
Best regards,
Yvan