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We can see a clear sinusoidal pattern, a sign of sustained vortex shedding process after 40s.This plot can be used to compute the correct value of Strouhal number. The problem is non-dimensionalized (D = 2, U = 1) and Sr = f*D/U = 0.0846 * 2 = 0.169. The results matches fairly well with the value 0.183 as reported by Williamson (link)

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titleCalculating Shedding Frequency
Wiki Markup
To accurately calculate the shedding frequency, open the {{cl-history}} file (saved previously in the same location where the original mesh was read) and plot the data using excel for better data representation and graphing option. Take an average of 10 shedding cycles (e.g 10 C{~}L~ peak).
\\
{latex}
\large
$$
{\rm{Period}} = {{T_2 - T_1} \over {10}}
$$
{latex}\\
\\
\\
{latex}
\large
$$
{\rm{f}} = {{1} \over {Period}}$$
{latex}\\
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\\
{latex}
\large
$$
{\rm{Sr}} = {fD \over U}
$$
{latex}\\
\\
An example of Lift Convergence Plot plotted using excel is shown below:
\\  !Excel Lift convergence_sm.jpg!\\
{newwindow:Higher Resolution Image}https://confluence.cornell.edu/download/attachments/107011456/Excel%20Lift%20convergence.jpg{newwindow}

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