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Old   May 4, 2010, 09:22
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Rick
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By that you mean drag and lift? I only have that in the monitors option, I don't have spin vector, drag is in x=1 and lift is y=1


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Have you set the direction of the spin vector and lift vector perpendicular?
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Old   May 4, 2010, 09:36
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Jouke de Baar
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In the boundary condition panel you can set something like spin vector or spin axis orientation? If for example cd is in x-direction and spin axis is in y-direction (which you should check) then cl should be in z-direction.
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Old   May 4, 2010, 11:07
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I put an image of the orientation of the mesh attached

In the boundary condition for the ball:
I have motion rotational and then a rotation-axis origin which I defined 0 for x,y,z
and I have rotation-axis direction in which I have 0 for x,y and 1 for z.

In the monitors I only have active the residuals, drag and lift. In the drag I have Force vector x=1 and in the lift I have force vector y=1,

I think it's ok...

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Originally Posted by jack1980 View Post
In the boundary condition panel you can set something like spin vector or spin axis orientation? If for example cd is in x-direction and spin axis is in y-direction (which you should check) then cl should be in z-direction.
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File Type: jpg Meshcoordinate.jpg (47.8 KB, 16 views)
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Old   May 4, 2010, 11:15
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Yes that should be ok.

Hmmm ... this is strange ...

Could you perhaps upload your case somewhere, such that I can have a look at it?
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Old   June 15, 2010, 06:51
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I have a question regarding the Magnus (or lift force) it's about the expression that is used to calculate the Magnus force, I've found 2 of them and don't know which is the right one
is it:

Fl=1/2*cl*\rho*A*v^2

or

Fl=1/2*cl*\rho*A*r*\omega*v

I'd really appreciate the help
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Old   June 15, 2010, 07:39
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They are both correct.

However the upper definition is more conventional. This will give the correct force if you use the cl from FLUENT.

Take care that A is the projected area of the sphere. ( \pi r^2 )
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Old   June 19, 2010, 18:37
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hello
I have another question, If you see the image I posted, it is a normal football where I did the analysis, I wanted to see more the edges and pattern, like this second image I found on the net
can anyone help?
best regards
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