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#1 |
Guest
Posts: n/a
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Dear all, I have been playing with Fluent a little recently and have been trying to replicate flow around a circular cylinder for Re of 200, 500, 1000. When comparing with experimental data, I notice that the trend in drag coefficient given by the simulation for increasing Re is opposite to that given by the experiment. I have followed fluent's own example for setting up low Re flow around a cylinder. Both pressure and momentum are second order. Pressure velocity coupling is PISO with the skewness-neighbor unchecked (again following Fluent's example). The fluid in question is water. Anyone have any suggestion as to why this may be occuring?
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#2 |
Guest
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Differences could be due to the type of turbulence model you're running as well as grid around the cylinder.
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#3 |
Guest
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At Re < 1000 it was my understanding that a turbulence model was not needed.
Basically, according to literature, for this Re range, CD should be decreasing. With my simulations, CD is increasing (slightly). |
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#4 |
New Member
Rishitosh Ranjan
Join Date: Dec 2012
Location: Trichirapalli, Tamilnadu, India
Posts: 22
Rep Power: 13 ![]() |
hiii..
i m also new in dis CFD area... i m working on flow over two side by side cylinders... @ Re= 100 and 200.. i got good results.. but i want to find out Strouhal number for all cases... i came to know by finding shedding frequency with help of FFT, using cofficient of lift data, in fluent 13.0 we can calculate Strouhal number... but i m getting helpess.. how to use FFT to find shedding frequency....????? ![]() ![]() -Rishi |
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#5 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,728
Rep Power: 66 ![]() ![]() ![]() |
FFT will give you amplitudes of oscillation for corresponding frequencies. You just need to look at the plotted FFT and notice which frequency has the highest amplitude. That amplitude should be the shedding frequency.
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#6 |
New Member
wesam
Join Date: Sep 2012
Posts: 23
Rep Power: 13 ![]() |
Hi
i have a problem with negative Cd. i want to know where is a mistake. i am in trouble please i need help thank you |
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Thread | Thread Starter | Forum | Replies | Last Post |
Flow over a Circular Cylinder | Sanjay | FLUENT | 25 | April 22, 2011 02:14 |
flow around circular cylinder...plz help | yousef | FLUENT | 4 | March 28, 2006 11:01 |
3D Flow over a circular cylinder | Srinivas | FLUENT | 3 | March 15, 2005 19:57 |
2D Flow over a circular cylinder | Jonathan | FLUENT | 2 | February 18, 2004 13:16 |
flow around a circular cylinder | Hanson He | Main CFD Forum | 0 | November 17, 1998 10:39 |