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Weekly Report

Weekly Report. Shervin Taghavi Nezhad December 2, 2008. Unsteady results for PR=1.5 in 2D.

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Weekly Report

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  1. Weekly Report Shervin Taghavi Nezhad December 2, 2008

  2. Unsteady results for PR=1.5 in 2D • We have started the code running 1st order accuracy. After reaching convergence we convert the code to 2nd order accuracy. For the current condition of PR=1.5 and cavity, no convergence was achieved so we switch the code to unsteady mode and ran it for 12 msec using time steps equal 1e-6 sec. • The unsteady run is done using 2nd order accuracy in time and space which tends to be less dissipative. • To monitor the flow behavior, we have put four probes in the flow • The pressure fluctuations with respect to time are plotted in slide 4

  3. The Mach Contour For the Unsteady 2D Case (t~12 msec)

  4. Pressure Fluctuation through time at 4 Locations

  5. Fast Fourier Transform for Pressure Fluctuations • The pressure fluctuations are not very informative, so we do a fft on them to get more information out of them • After about 7 msec, the pressure fluctuation at the probes seem to follow an almost periodic behavior, so we implement fft only on the last 5 msec • For fft, Matlab is used • The x axis in all the following figures shows the frequency • The y axis shows the logarithm of the amplitude of fft of pressure fluctuations. The relation used for the y axis is:

  6. The fft of pressure fluctuation at the boltWe can observe two peaks at 2.5KHz and 3KHz and one at 600Hz

  7. The fft of pressure fluctuation at the cavityWe can observe two peaks at 2.5KHz and 3KHz and one at 600Hz

  8. The fft of pressure fluctuation at the vortex, which is the shear locationWe can observe three peaks at 2.5KHz and 3KHz and 6KHz

  9. The fft of pressure fluctuation at the exitWe can observe two peaks at 2.5KHz and 3KHz and one at 600Hz

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