Why are the data points not being correctly colored to scale in my quiver plot?

I want to create a quiver plot that can descibe a flow field with particle angle and velocity. I want to show the magnitude of the velocity field by colorizing each quiver-point with a color from a scale bar.

The issue I am facing is that some of the arrows are not correctly colored. For example, the yellow arrow in the attached image should represent the fastest moving particle and should be colored red to describe it's velocity of 59.56 mm/s. However right now it is being represented in yellow and I do not know why. All velocites are being normalized and compared to the maximum velocity value within the variable "velocities".

Thanks for the help! The code can be seen below.

% Acoustic Streaming Particle Tracking in Pressurized Conditions
% Hydrostatic Conditions
% h = 0 ft

clear all
clc

%% Particle Mapping in Crossflow Effects

ArrowLength = 300;
ArrowHeadSize = 5;
ArrowLineWidth = 1.5;   % Adjust this value to change the line width of the arrows
ArrowScale = 1;         % Adjust this value to change the size or scale of the arrows

% Distance from tip - 500 um

position500_1 = [-500, 500]; % x and y coordinates of arrow 1
angle500_1 = 360; % angle in degrees for arrow 1
velocity500_1 = 3.255569464; % velocity value for arrow 1

position500_2 = [0, 500]; % x and y coordinates of arrow 2
angle500_2 = 93.168; % angle in degrees for arrow 2
velocity500_2 = 59.56398362; % velocity value for arrow 2

position500_3 = [500, 500]; % x and y coordinates of arrow 3
angle500_3 = 190.248; % angle in degrees for arrow 3
velocity500_3 = 4.232935719; % velocity value for arrow 3

position500_4 = [-1000, 500]; % x and y coordinates of arrow 4
angle500_4 = 360; % angle in degrees for arrow 4
velocity500_4 = 2.313458035; % velocity value for arrow 4

position500_5 = [1000, 500]; % x and y coordinates of arrow 5
angle500_5 = 184.236; % angle in degrees for arrow 5
velocity500_5 = 2.284196058; % velocity value for arrow 5

% Distance from tip - 1000 um

position1000_1 = [-500, 1000]; % x and y coordinates of arrow 1
angle1000_1 = 105.427; % angle in degrees for arrow 1
velocity1000_1 = 6.675189766; % velocity value for arrow 1

position1000_2 = [0, 1000]; % x and y coordinates of arrow 2
angle1000_2 = 93.36; % angle in degrees for arrow 2
velocity1000_2 = 20.93672533; % velocity value for arrow 2

position1000_3 = [500, 1000]; % x and y coordinates of arrow 3
angle1000_3 = 81.254; % angle in degrees for arrow 3
velocity1000_3 = 5.836827773; % velocity value for arrow 3

position1000_4 = [-1000, 1000]; % x and y coordinates of arrow 4
angle1000_4 = 360; % angle in degrees for arrow 4
velocity1000_4 = 0.781474674; % velocity value for arrow 4

position1000_5 = [1000, 1000]; % x and y coordinates of arrow 5
angle1000_5 = 199.44; % angle in degrees for arrow 5
velocity1000_5 = 1.565790925; % velocity value for arrow 5

% Collecting the velocities from all data points
velocities = [velocity500_1, velocity500_2, velocity500_3, velocity500_4, velocity500_5, ...
              velocity1000_1, velocity1000_2, velocity1000_3, velocity1000_4, velocity1000_5];

% Plotting the arrows
figure; hold on;

% 500 um 
plotArrows(position500_1, angle500_1, velocity500_1, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position500_2, angle500_2, velocity500_2, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position500_3, angle500_3, velocity500_3, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position500_4, angle500_4, velocity500_4, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position500_5, angle500_5, velocity500_5, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
% 1000 um 
plotArrows(position1000_1, angle1000_1, velocity1000_1, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position1000_2, angle1000_2, velocity1000_2, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position1000_3, angle1000_3, velocity1000_3, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position1000_4, angle1000_4, velocity1000_4, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position1000_5, angle1000_5, velocity1000_5, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);

hold off;
axis equal;
xlim([-1500, 1500]);
ylim([-0, 4500]);
title('Acoustic Streaming Particle Tracking');
xlabel('X-coordinate');
ylabel('Y-coordinate');

% Define the getColor function
function color = getColor(velocity, velocities, maxVelocity)
    colormap('jet');
    c = colorbar;
    caxis([min(velocities), maxVelocity]);  % Adjusted to include min(velocities)
    color = colormap(c);
    color = interp1(linspace(min(velocities), maxVelocity, size(color, 1)), color, velocity);
end

% Define the plotArrows function
function plotArrows(position, angle, velocity, velocities, maxVelocity, ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth)
    quiver(position(1), position(2), ArrowScale * ArrowLength * cosd(angle), ArrowScale * ArrowLength * sind(angle), ...
        'Color', getColor(velocity, velocities, maxVelocity), 'MaxHeadSize', ArrowHeadSize, 'LineWidth', ArrowLineWidth);
end

Answer 1

[Voss]

See the change below in getColor.

% Acoustic Streaming Particle Tracking in Pressurized Conditions
% Hydrostatic Conditions
% h = 0 ft

clear all
clc

%% Particle Mapping in Crossflow Effects

ArrowLength = 300;
ArrowHeadSize = 5;
ArrowLineWidth = 1.5;   % Adjust this value to change the line width of the arrows
ArrowScale = 1;         % Adjust this value to change the size or scale of the arrows

% Distance from tip - 500 um

position500_1 = [-500, 500]; % x and y coordinates of arrow 1
angle500_1 = 360; % angle in degrees for arrow 1
velocity500_1 = 3.255569464; % velocity value for arrow 1

position500_2 = [0, 500]; % x and y coordinates of arrow 2
angle500_2 = 93.168; % angle in degrees for arrow 2
velocity500_2 = 59.56398362; % velocity value for arrow 2

position500_3 = [500, 500]; % x and y coordinates of arrow 3
angle500_3 = 190.248; % angle in degrees for arrow 3
velocity500_3 = 4.232935719; % velocity value for arrow 3

position500_4 = [-1000, 500]; % x and y coordinates of arrow 4
angle500_4 = 360; % angle in degrees for arrow 4
velocity500_4 = 2.313458035; % velocity value for arrow 4

position500_5 = [1000, 500]; % x and y coordinates of arrow 5
angle500_5 = 184.236; % angle in degrees for arrow 5
velocity500_5 = 2.284196058; % velocity value for arrow 5

% Distance from tip - 1000 um

position1000_1 = [-500, 1000]; % x and y coordinates of arrow 1
angle1000_1 = 105.427; % angle in degrees for arrow 1
velocity1000_1 = 6.675189766; % velocity value for arrow 1

position1000_2 = [0, 1000]; % x and y coordinates of arrow 2
angle1000_2 = 93.36; % angle in degrees for arrow 2
velocity1000_2 = 20.93672533; % velocity value for arrow 2

position1000_3 = [500, 1000]; % x and y coordinates of arrow 3
angle1000_3 = 81.254; % angle in degrees for arrow 3
velocity1000_3 = 5.836827773; % velocity value for arrow 3

position1000_4 = [-1000, 1000]; % x and y coordinates of arrow 4
angle1000_4 = 360; % angle in degrees for arrow 4
velocity1000_4 = 0.781474674; % velocity value for arrow 4

position1000_5 = [1000, 1000]; % x and y coordinates of arrow 5
angle1000_5 = 199.44; % angle in degrees for arrow 5
velocity1000_5 = 1.565790925; % velocity value for arrow 5

% Collecting the velocities from all data points
velocities = [velocity500_1, velocity500_2, velocity500_3, velocity500_4, velocity500_5, ...
              velocity1000_1, velocity1000_2, velocity1000_3, velocity1000_4, velocity1000_5];

% Plotting the arrows
figure; hold on;

% 500 um 
plotArrows(position500_1, angle500_1, velocity500_1, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position500_2, angle500_2, velocity500_2, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position500_3, angle500_3, velocity500_3, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position500_4, angle500_4, velocity500_4, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position500_5, angle500_5, velocity500_5, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
% 1000 um 
plotArrows(position1000_1, angle1000_1, velocity1000_1, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position1000_2, angle1000_2, velocity1000_2, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position1000_3, angle1000_3, velocity1000_3, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position1000_4, angle1000_4, velocity1000_4, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);
plotArrows(position1000_5, angle1000_5, velocity1000_5, velocities, max(velocities), ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth);

hold off;
axis equal;
xlim([-1500, 1500]);
ylim([-0, 4500]);
title('Acoustic Streaming Particle Tracking');
xlabel('X-coordinate');
ylabel('Y-coordinate');

% Define the getColor function
function color = getColor(velocity, velocities, maxVelocity)
    color = colormap('jet');
    c = colorbar;
    caxis([min(velocities), maxVelocity]);  % Adjusted to include min(velocities)
    % color = colormap(c);
    color = interp1(linspace(min(velocities), maxVelocity, size(color, 1)), color, velocity);
end

% Define the plotArrows function
function plotArrows(position, angle, velocity, velocities, maxVelocity, ArrowLength, ArrowScale, ArrowHeadSize, ArrowLineWidth)
    quiver(position(1), position(2), ArrowScale * ArrowLength * cosd(angle), ArrowScale * ArrowLength * sind(angle), ...
        'Color', getColor(velocity, velocities, maxVelocity), 'MaxHeadSize', ArrowHeadSize, 'LineWidth', ArrowLineWidth);
end

[Voss]

@Kieran Fung: Did this answer work for you?