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February 16, 2003, 23:29 
Velocity Fields/Stream Equations

#1 
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hi
I am making a small cfd code and want to test my output in different flow fields i want to test my output in a rotational / translation/ revolving flow field and any combination of these . could anyone tell me how to get the stream function corresponding to these thanks a newbie 

February 17, 2003, 03:37 
Re: Velocity Fields/Stream Equations

#2 
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If you have the velocity field tecplot can plot the streamlines. You can even use matlab (stream2, stream3, streamline).


February 17, 2003, 13:34 
Re: Velocity Fields/Stream Equations

#3 
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"rotational / translation/ revolving flow field"?
Does this mean it's a three dimensional (x  y  z) flow? If so, the stream function will be a vector function and so not too useful for visualization of the flow. To get a stream function that's scalar, your flow must be 2d, either Cartesian (x  y) or cylindrical (r  z although a rotational component can be included if it's axisymmetric). You can visualize the flow using virtual particle traces or streaklines. Generate the tracks for those by for a series of points (x, y, z)_i by x_i+1 = x_i + u(x_i, y_j, z_k)*dx with similar for y_j+1 and z_(k+1). Hope this helps. 

February 17, 2003, 14:53 
Re: Velocity ... corrected post!

#4 
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My previous reply to this was a bit hasty. See correction in the partical trace discussion below:
"rotational / translation/ revolving flow field"? Does this mean it's a three dimensional (x  y  z) flow? If so, the stream function will be a vector function and so not too useful for visualization of the flow. To get a stream function that's scalar, your flow must be 2d, either Cartesian (x  y) or cylindrical (r  z although a rotational component can be included if it's axisymmetric). You can visualize the flow using virtual particle traces or streaklines. Generate the tracks for those by for a series of points (x, y, z)_i by *** Corrected text below *** x_i+1 = x_i + u(x_i, y_i, z_i)*dx with similar for y_i+1 and z_(i+1). For the particle coordinates (x, y, z), the index "i" counts the locations generated for the virtual particle through the flow field. It is NOT an index for a grid line or node. Hope this helps. 

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