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October 18, 2010, 22:35 
theta volocity in cylindrical coordinate

#1 
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wuyu
Join Date: Mar 2010
Posts: 20
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I am modeling a fluid impact on a cylinder. Therefore I set it in the cylindrical coordinate. The veloctiy at impact will be resolved into two components, radial and azimuthal velocity. Let's say velocity is 1 m/s, the fluid impacts on the cylinder, not through the circle center. Assume the angle is 30 degrees, the diameter of the cylinder is 1mm. Then the radial velocity is 0.86m/s, the azimuthal velocity is sin30/0.0005=10000 rad/s. But I found the fluid flew away from the computational domain within a quite short time. But physically it should impact on the cylinder. Is the velocity in y direction (theta) in a unit of radian/s?


October 23, 2010, 15:07 

#2  
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michael barkhudarov
Join Date: Mar 2009
Posts: 329
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I can't quite picture this in cylindrical coordinates. Where are you setting the inlet velocity?
Why not do it in a Cartesian grid? Quote:


October 31, 2010, 05:02 

#3 
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wuyu
Join Date: Mar 2010
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I am actually modeling a droplet, so there is no inlet velocity issue. And I want to postprocess the data close to the cylinder surface, if in cartesian coordinate, is it possible to create a slice parallel to the curvature surface?


November 1, 2010, 00:49 

#4  
Senior Member
michael barkhudarov
Join Date: Mar 2009
Posts: 329
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Quote:
If you are trying to define an initial uniform droplet velocity moving towards the cylindrical axis, I don't think you can do it using the available input in FLOW3D (if understand your problem). It is much easier in a Cartesian grid. 

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