i want to plot the vertical velocity graph in multiple location in cross section plan into the graph like the post image.

this is the velocity data in every cross section. i dont understand how to draw in matlab?

Answer 1

[William Rose]

@ANIRBAN,

It would be helpful if you would provide some actual data and an explanation in words of what you want to plot.

It appears that you wish to plot velocities at varoius x,y, and z values. I will assume that the velocity is in the y-direction, since you plot it on the y-axis.

If you want a 3-D plot, use quiver3().

X = [2,2,2,2,2,2,2,2,2,8,8,8,8,8,8,8,8,8,20,20,20,20,20,20,20,20,20];
Z = [0,0,0,.4,.4,.4,.8,.8,.8,0,0,0,.4,.4,.4,.8,.8,.8,0,0,0,.4,.4,.4,.8,.8,.8];
Y = [-2,0,2,-2,0,2,-2,0,2,-2,0,2,-2,0,2,-2,0,2,-2,0,2,-2,0,2,-2,0,2];
disp([size(X),size(Y),size(Z),size(X-12),size(Z+.8),size(5-Y.^2)])

     1    27     1    27     1    27     1    27     1    27     1    27

U = zeros(1,27);
V = (Z+.8).*(X+12).*(5-Y.^2);
W = zeros(1,27);
quiver3(X,Y,Z,U,V,W);
xlabel('X'), ylabel('Y'), zlabel('Z')

That example does not look great due to the sparsity of arrows, but you can try it.

If you want a plot more like the image you shared, make three plots with quiver(), which is the 2D version.

Good luck with your work.

[William Rose]

@ANIRBAN,

Here's another example of using quiver3 and quiver.

x=[2,8,20]; y=[-2:.4:2]; z=[.1:.1:.9];
[X,Y,Z]=meshgrid(x,y,z);
U=zeros(size(X)); W=zeros(size(X));
V=(X-9).*(.2-(Z-.5).^2).*(5-Y.^2);
quiver3(X,Y,Z,U,V,W);
xlabel('X'), ylabel('Y'), zlabel('Z'); title('Velocity')

Or make three 2-D plots:

figure;
subplot(311); 
quiver(squeeze(Y(:,3,:)),squeeze(Z(:,3,:)),squeeze(V(:,3,:)),squeeze(W(:,3,:)))
xlabel('Y'); ylabel('Z'); title('X=20');
subplot(312);
quiver(squeeze(Y(:,2,:)),squeeze(Z(:,2,:)),squeeze(V(:,2,:)),squeeze(W(:,2,:)))
xlabel('Y'); ylabel('Z'); title('X=8');
subplot(313); 
quiver(squeeze(Y(:,1,:)),squeeze(Z(:,1,:)),squeeze(V(:,1,:)),squeeze(W(:,1,:)))
xlabel('Y'); ylabel('Z'); title('X=2');

A problem with the three plots above is that the length of the arrows is auto-scaled independently on each subplot, so the differences in velocities across plots are not apparent. Another problem is that the horizontal axis ranges are different in different subplots. Therefore turn off autoscaling, and set the horizontal axis limits manually for each subplot:

figure;
V=V/25;         % rescale the y-axis velocities for plotting
subplot(311); 
quiver(squeeze(Y(:,3,:)),squeeze(Z(:,3,:)),squeeze(V(:,3,:)),squeeze(W(:,3,:)),'AutoScale',0)
xlabel('Y'); ylabel('Z'); title('X=20'); xlim([-2.5,2.5])
subplot(312);
quiver(squeeze(Y(:,2,:)),squeeze(Z(:,2,:)),squeeze(V(:,2,:)),squeeze(W(:,2,:)),'AutoScale',0)
xlabel('Y'); ylabel('Z'); title('X=8'); xlim([-2.5,2.5])
subplot(313); 
quiver(squeeze(Y(:,1,:)),squeeze(Z(:,1,:)),squeeze(V(:,1,:)),squeeze(W(:,1,:)),'AutoScale',0)
xlabel('Y'); ylabel('Z'); title('X=2'); xlim([-2.5,2.5])

Good luck.