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Showing results 1 to 19 of 19 Search took 0.00 seconds. Search: Posts Made By: jack1980

Forum: FLUENT June 15, 2010, 07:39

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 They are both correct. However the upper... 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. (...

Forum: FLUENT May 4, 2010, 11:15

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Yes that should be ok. Hmmm ... this is... 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?

Forum: FLUENT May 4, 2010, 09:36

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 In the boundary condition panel you can set... 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...

Forum: FLUENT May 4, 2010, 08:57

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Have you set the direction of the spin vector and... Have you set the direction of the spin vector and lift vector perpendicular?

Forum: FLUENT May 4, 2010, 08:43

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 ang_vel = flow_vel * Sp / radius ang_vel = flow_vel * Sp / radius

Forum: FLUENT May 4, 2010, 07:40

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Hi, There is a lot of information on:... Hi, There is a lot of information on: http://www.grc.nasa.gov/WWW/K-12/airplane/beach.html Here they have a ideal lift for both the cylinder and the sphere. It's all in lb/ft etc. so beware of the...

Forum: FLUENT May 3, 2010, 16:26

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Hi, as far as I understand these are experimental... Hi, as far as I understand these are experimental values for a scale model soccer ball, from a book I have here. The spin parameter is defined: radius X angular_velocity / flow_velocity The...

Forum: FLUENT May 3, 2010, 15:37

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 where Re=2.1e5 where Re=2.1e5

Forum: FLUENT May 3, 2010, 15:36

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Hi, here I have a plot that gives experimental... Hi, here I have a plot that gives experimental values for a soccer ball. The spin parameter (R omega / u) ranges 0.00 to 0.20. The magnus coefficient is almost linear and coincidentally appears to be...

Forum: FLUENT May 3, 2010, 03:16

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 There is some data in: Sarah Barber, Matt... There is some data in: Sarah Barber, Matt Carre, Soccer Ball Aerodynamics which is a chapter of the book: Martin Peters, Computational Fluid Dynamics for Sport Simulation, Springer-Verlag...

Forum: FLUENT April 30, 2010, 15:12

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Hi, it seems your in business now. There is... Hi, it seems your in business now. There is definitely an effect in the velocity and pressure plots, and you are getting lift. The lift might seem a bit small, but it could be ok for this case. As a...

Forum: FLUENT April 30, 2010, 12:21

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Hi, when I looked at your results again, I saw... Hi, when I looked at your results again, I saw they actually show a slight asymmetry. This is good news, as it indicates that your moving wall boundary condition is actually at work (assuming you're...

Forum: FLUENT April 30, 2010, 11:53

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Sorry that was a bit unclear. That part is the... Sorry that was a bit unclear. That part is the results. Where you can set 1st or 2nd upwind under solution. Anyway, with a rotating wall you should be getting some lift here, one way or the...

Forum: FLUENT April 30, 2010, 07:47

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 By the way I'm not sure about the reference area.... By the way I'm not sure about the reference area. I think I put it at 1 m, but probably it should be 2m??

Forum: FLUENT April 30, 2010, 07:44

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 That is really strange ... I've copied some... That is really strange ... I've copied some of my settings. I am calculating in 2D (but not axisymmetric). My sphere radius is 1 m. My domain is a bit small of course, but it's just a quick...

Forum: FLUENT April 29, 2010, 16:09

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Hi, gave it a try in 2D. For my settings I found:... Hi, gave it a try in 2D. For my settings I found: 0 rad/s -> cl = -5e-5, cd = 2.7 5 rad/s -> cl = -7, cd = 3.9 Here's a picture of the stream functions: ...

Forum: FLUENT April 28, 2010, 12:23

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 I might misunderstand but isn't it just another... I might misunderstand but isn't it just another word for lift? Remind, you can actually specify in which sideways direction you want to calculate the lift coefficient. It can be in any direction...

Forum: FLUENT April 28, 2010, 12:05

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 What is a Magnus coefficient? What is a Magnus coefficient?

Forum: FLUENT April 28, 2010, 11:15

Replies: 46 Rotating a sphere Views: 10,907 Posted By jack1980 Why not just have a stationary sphere, then set... Why not just have a stationary sphere, then set boundary conditions as (rotational) moving wall?

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