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Stream ribbons illustrate direction of flow, similar to stream lines, but can also show rotation about the flow axis by twisting the ribbon-shaped flow line. The streamribbon function enables you to specify a twist angle (in radians) for each vertex in the stream ribbons.
When used in conjunction with the curl function, streamribbon is useful for displaying the curl angular velocity of a vector field. The following example illustrates this technique.
Load and select a region of interest in the wind data set using subvolume. Plotting the full data set first can help you select a region of interest.
load wind lims = [100.64 116.67 17.25 28.75 -0.02 6.86]; [x,y,z,u,v,w] = subvolume(x,y,z,u,v,w,lims);
Calculate the curl angular velocity and the wind speed.
cav = curl(x,y,z,u,v,w); wind_speed = sqrt(u.^2 + v.^2 + w.^2);
stream3 calculates the stream line vertices with a step size of .5.
streamribbon scales the width of the ribbon by a factor of 2 to enhance the visibility of the twisting (which indicates curl angular velocity).
streamribbon returns the handles of the surface objects it creates, which are then used to set the color to red (FaceColor), the color of the surface edges to light gray (EdgeColor), and slightly increase the brightness of the ambient light reflected when lighting is applied (AmbientStrength).
[sx sy sz] = meshgrid(110,20:5:30,1:5); verts = stream3(x,y,z,u,v,w,sx,sy,sz,.5); h = streamribbon(verts,x,y,z,cav,wind_speed,2); set(h,'FaceColor','r',... 'EdgeColor',[.7 .7 .7],... 'AmbientStrength',.6)
axis(volumebounds(x,y,z,wind_speed)) grid on view(3) camlight right;