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flow structure around cylinder

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Old   April 3, 2013, 07:24
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  #21
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mahdi
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Originally Posted by jayrup View Post
To calculate the Forces on component you need to enable the output for Component in Component properties we have an output option with Pressure & Shear force output.
In your case the Lift force will be component 1 y fluid force : Pressure + shear & Drag force will be component 1 x fluid force : Pressure + shear in Analyze tab > Probe Tab > General History in Flow-3d v10.1.Don't forget to define the gravity.

Regards
Jay
thank you jay
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Old   April 3, 2013, 09:23
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Quote:
Originally Posted by jayrup View Post
To calculate the Forces on component you need to enable the output for Component in Component properties we have an output option with Pressure & Shear force output.
In your case the Lift force will be component 1 y fluid force : Pressure + shear & Drag force will be component 1 x fluid force : Pressure + shear in Analyze tab > Probe Tab > General History in Flow-3d v10.1.Don't forget to define the gravity.

Regards
Jay
Hello jay
when I run software, below message appears.
"There is no reference pressure."

Do you have an advice to solve it?

Regards,
Mahdi
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Old   April 4, 2013, 02:30
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Quote:
Originally Posted by mahdi1 View Post
Hello jay
when I run software, below message appears.
"There is no reference pressure."

Do you have an advice to solve it?

Regards,
Mahdi
Hi Mahdi,

It is just a warning message from the solver that initial pressure is not given. And solver takes care of that & calculates iteratively in next time step. You can ignore it.
If you really don't want to ignore it you can define uniform pressure in Initial tab & Void Initial state > Pressure. If you are simulating no sharp interface case then in Initial Tab > Pressure > Hydrostatic pressure value takes care of that.
Regards
Jay
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Old   April 8, 2013, 14:38
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mahdi
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Quote:
Originally Posted by jayrup View Post
Hi Mahdi,

It is just a warning message from the solver that initial pressure is not given. And solver takes care of that & calculates iteratively in next time step. You can ignore it.
If you really don't want to ignore it you can define uniform pressure in Initial tab & Void Initial state > Pressure. If you are simulating no sharp interface case then in Initial Tab > Pressure > Hydrostatic pressure value takes care of that.
Regards
Jay
Thanks Jay
Do you know that, how I can print stream line in flow-3d?
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Old   April 6, 2014, 20:43
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Hamed
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Originally Posted by pyxbird View Post
Dear all,
As you can see in the picture, velocity=45cm/s, diameter=30cm, Re=13500, RNG model is used, the grid is fine enough, the flow is steady, usually in this condition the turbulence behind the cylinder should be intensive, vortices should be seen. However from the streamlines we can see that the model performs not so good, why?
Hi
There is no problem with mesh resolution !! Vortex shedding takes time for shaping it is not immediate. Try simulating for about 30s ... and do not care about the warnings that say flow is nearly steady..
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