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The Umean of a flow around a cube calculated in Openfoam looks like instantaneous

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Old   June 14, 2016, 17:31
Default The Umean of a flow around a cube calculated in Openfoam looks like instantaneous
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Hi, everyone

I'm trying to study the flow features around a cube placed in an uniform flow (without walls). However, the mean velocity calculated in Openfoam is just like instantaneous, and differs with time. I have uploaded the streamline (surfaceLIC) of Umean colored by magnitude in X-Z plane through the center line at different times, 4.74s, 6.98s and 8.1s. X is the streamwise direction, Y is the spanwise direction and Z is vertical in the cross-stream direction. What's more, flow characteristics in X-Y plane is not the same as X-Z plane. The time is long enough and the flow is statistical steady, since the mean value of Cd, Cl and Cs is steady as shown in attached pictures, in which these parameters are averaged every 1s. Have anyone encounter similar questions or could anyone give me some advice? The phenomenon confused me a lot and I can't validate my case due to the lack of related experimental study. Thank you very much!

Best regards
Yanan
Attached Images
File Type: jpg 4.74s.jpg (97.6 KB, 49 views)
File Type: jpg 6.98s.jpg (107.2 KB, 40 views)
File Type: jpg 8.1s.jpg (86.8 KB, 32 views)
File Type: png Mean of Cd Cl Cs.png (7.9 KB, 30 views)
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Old   June 14, 2016, 18:04
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Quote:
Originally Posted by jiaodanuma View Post
Hi, everyone

I'm trying to study the flow features around a cube placed in an uniform flow (without walls). However, the mean velocity calculated in Openfoam can't achieve an averaged vorticity in the wake region, which is just like instantaneous, and differs with time. I have uploaded the streamline (surfaceLIC) of Umean colored by magnitude in X-Z plane through the center line at different times, 4.74s, 6.98s and 8.1s. X is the streamwise direction, Y is the spanwise direction and Z is vertical in the cross-stream direction. What's more, flow characteristics in X-Y plane is not the same as X-Z plane. The time is long enough and the flow is statistical steady, since the mean value of Cd, Cl and Cs is steady as shown in attached pictures, in which these parameters are averaged every 1 s. Have anyone encounter similar questions or could anyone give me some advice? The phenomenon confused me a lot and I can't validate my case due to the lack of related experimental study. Thank you very much!

Best regards
Yanan
Is the surfaceLIC a Paraview tool? If so, which version?
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Old   June 14, 2016, 18:11
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Yes I use the command "vorticity -latestTime" in openFoam to calculate the vorticity. And sorry for the misunderstanding description in the question. The "vorticity" in the question means constant recirculation region.
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Old   June 14, 2016, 18:13
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Is the surfaceLIC a Paraview tool? If so, which version?
Yes I use the command "vorticity -latestTime" in openFoam to calculate the vorticity. And sorry for the misunderstanding description in the question. The "vorticity" in the question means constant recirculation region.
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Old   June 14, 2016, 18:16
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Is the surfaceLIC a Paraview tool? If so, which version?
Yes. It's ParaView 5.0.1 (64 bit)
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