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title | Calculating Shedding Frequency |
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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 CL peak).
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$$
{\rm{Period}} = {{T_2 - T_1} \over {10}}
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$$
{\rm{f}} = {{1} \over {Period}}$$
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$$
{\rm{Sr}} = {fD \over U}
$$
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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/107011458/Excel%20Lift%20convergence.jpg{newwindow}
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| Higher Resolution Image |
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| Higher Resolution Image |
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https://confluence.cornell.edu/download/attachments/107011458/pressure%20contour%20coefficient%20plotpressure%20coefficient%20contour%20plot.jpg |
The contour shows a clear asymmetric pattern in the flow. The local pressure minima (the green patch downstream) are the center of the vortices.
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