MATLAB: Plotting streamlines in matlab.

streamlines

I am trying plot streamlines using the streamlinefunction. The number of streamlines i'm getting streamlines are way too less. I am attaching the code and the data file containing the velocity components and their co-ordinates. please help me in resolving the issue.

Best Answer

Just increased number of starting points

n = 100;                 % number of streamlines
starting_x = zeros(1,n); % starting points for streamlines
starting_y = linspace(-0.1,0.1,n);

Related Solutions

MATLAB: Plotting streamlines from velocity components

Michael,

I've got some code below that plots slices and streamlines for your data but the data itself is odd. It looks like you've got an impeller blowing into a tank but the velocity vector that's coming out of it is normal to the impeller. However, that's what the quiver arrows show so the streamlines follow the arrows. So at least, you can now look at your streamlines as you work on the velocities (if necessary.

Good luck!

    clearvars
    load 'velocity components.mat'
    mag_V = sqrt(Vx.^2 + Vy.^2 + Vz.^2);
    % Filtering out zero velocity walls.
    index = mag_V > 0.1;
    xx = x(index);
    yy = y(index);
    zz = z(index);
    Vxx = Vx(index);
    Vyy = Vy(index);
    Vzz = Vz(index);
    FVx = scatteredInterpolant(xx,yy,zz,Vxx,'linear','none');
    FVy = scatteredInterpolant(xx,yy,zz,Vyy,'linear','none');
    FVz = scatteredInterpolant(xx,yy,zz,Vzz,'linear','none');
    % This is a very ugly grid for your problem but it works.
    % A cylindrical grid would probably be more resource efficient
    elements = 40; % how many subdivisions per dimensions.
    % Mind you, this is 3D. Total memory gets large fast
    [X3, Y3, Z3] = meshgrid(linspace(min(x),max(x),elements),...
        linspace(min(y),max(y),elements),...
        linspace(min(z),max(z),elements));
    V3x = FVx(X3,Y3,Z3);
    V3y = FVy(X3,Y3,Z3);
    V3z = FVz(X3,Y3,Z3);
    mag_V3 = sqrt(V3x.^2 + V3y.^2 + V3z.^2); % velocity vector magnitude
    starting_x = zeros(5,5); % starting points for streamlines
    [starting_y, starting_z] = meshgrid(linspace(-0.005,.005,5), ...
        linspace(-0.005,.005,5));
    figure(1)
    clf
    plot3(x,y,z,'.k','MarkerSize',4);
    hold on
    quiver3(x,y,z, Vx,Vy,Vz);
    h = slice(X3,Y3,Z3,mag_V3,[],0,-0.02:.02:0);
    set(h,'EdgeColor','w','FaceAlpha',0.75');
    h = streamline(X3,Y3,Z3,V3x,V3y,V3z,starting_x,starting_y,starting_z);
    set(h,'LineColor','r','LineWidth',4);
    axis equal
    grid on
    hold off

MATLAB: Help with Elastic Collision

You need to be careful about pre and post collision velocities, and the boundary checks:

t=0;
dt=0.5;
x1=1;
y1=0;
v1x=0;
v1y=0;
m1=1;
% centers = [x1, y1];
x2=-8;
y2=0;
v2x=2;
v2y=0;
m2=1;
% centers2 = [x2, y2];
% t=0, plot position of particles
subplot (3, 1, 1)
plot ([-10, 10], [-10, 10], 'w')
% obj1 = viscircles(centers,1)
% obj2 = viscircles (centers2, 1)
r1 = rectangle ('Position', [x1,y1,1,1], 'FaceColor', 'r', 'Curvature', [1,1]);
r2 = rectangle ('Position', [x2,y2,1,1], 'FaceColor', 'b', 'Curvature', [1,1]);
axis ([-10 10 -10 10]);
subplot (3, 1, 2)
plot (t, x1)
plot (t, x2)
xlabel ('Time')
ylabel ('Position-X')
subplot (3, 1, 3)
plot  (t, y1)
plot  (t, y2)
xlabel ('Time')
ylabel ('Position-Y')
xx1 = [ ];
xx2 = [ ];
yy1 = [ ];
yy2 = [ ];
% Start moving :)
while t < 100
    % Update "old" values
    v1xold = v1x; v2xold = v2x; v1yold = v1y; v2yold = v2y;
    
    if 1 < sqrt((x2-x1)^2+(y2-y1)^2)
        x1 =  x1 + (v1x * dt);
        x2 =  x2 + (v2x * dt);  
        y1 =  y1 + (v1y * dt);
        y2 = y2 + (v2y * dt);
        xx1 = [xx1, x1];
        xx2 = [xx2, x2];
        yy1 = [yy1, y1];
        yy2 = [yy2, y2];
       
    else   % Use "old" values on RHS
        v1x = ((m1-m2)/(m1+m2))*v1xold + ((2*m2)/(m1+m2)) * v2xold; 
        v1y = ((m1-m2)/(m1+m2))*v1yold + ((2*m2)/(m1+m2)) * v2yold;
        
        v2x = ((m2-m1)/(m1+m2))*v2xold + ((2*m1)/(m1+m2)) * v1xold;
        v2y = ((m2-m1)/(m1+m2))*v2yold + ((2*m1)/(m1+m2)) * v1yold;
        x1 =  x1 + (v1x * dt);
        x2 =  x2 + (v2x * dt);  
    
        y1 =  y1 + (v1y * dt);
        y2 =  y2 + (v2y * dt);
        
        
        xx1 = [xx1, x1];
        xx2 = [xx2, x2];
        yy1 = [yy1, y1];
        yy2 = [yy2, y2];
    end
    % At Boundary - Turn Direction
            if x1+dt*v1x>9
                v1x= -v1x;
            end
            if x2+dt*v2x>9
                v2x=-v2x;
            end
            if x1+dt*v1x<-10
                v1x=abs(v1x);
            end
            if x2+dt*v2x<-10
                v2x=abs(v2x);
            end
            if y1+dt*v1y>9
                v1y=-v1y;
            end
            if y2+dt*v2y>9
                v2y=-v2y;
            end
            if y1+dt*v1y<-10
                v1y=abs(v1y);
            end
            if y2+dt*v2y<-10
                v2y=abs(v2y);
            end
            
 
    %update the position of the rectangles 
    set(r1,'Position', [x1,y1,1,1]);
    set(r2,'Position', [x2,y2,1,1]);
    
    subplot (3, 1, 2)
    plot (t, x1,'ro',t,x2,'bs')
    axis([0 100 -10 10])
    xlabel ('Time')
    ylabel ('Position-X')
    
    subplot (3, 1, 3)
    plot (t, y1,'ro',t,y2,'bs')
    axis([0 100 -10 10])
    xlabel ('Time')
    ylabel ('Position-Y')
    drawnow
      t= t+ dt;
 end

Best Answer

Related Solutions

MATLAB: Plotting streamlines from velocity components

MATLAB: Help with Elastic Collision

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