how can I plot fluid through the cylinders

%t = 0:pi/18:2*pi;  y=0:.01:3;x=0:.01:3;
t = 0:pi/20:2*pi;  y=0:.01:5;x=0:.01:5;
%[X,Y,Z] = cylinder(.8*(1+.06*sin(5*t)));
[X,Y,Z] = cylinder(.8*(1+.06*sin(5*t)));
surfl(X,Z,Y)
hold on
%[X,Y,Z] = cylinder(1.8*(1+.06*sin(5*t)));
[X,Y,Z] = cylinder(1.8*(1+.06*sin(5*t)));
surfl(X,Z,Y)
%title('$\lambda=5,\epsilon=0.06$','Interpreter','latex','FontSize',11,'FontName','TiemsNewRoman','FontWeight','Normal');
shading interp
colormap(gray);
axis square
axis off

Answer 1

[Shlok]

Hi Shreen,

To illustrate fluid flow within the cylindrical geometry, an effective approach is to introduce an inner cylinder that represents the fluid. This inner core can be visually distinguished using a different colormap and some transparency, helping it stand out from the outer structure.

For example:

t = 0:pi/20:2*pi;
[Xf, Yf, Zf] = cylinder(0.6 * (1 + 0.06 * sin(5 * t)));
Zf = Zf * 3;
fluid = surf(Xf, Yf, Zf, Zf, 'FaceAlpha', 0.6, 'EdgeColor', 'none');
axis off

To enhance the visualization and simulate fluid motion, animate the inner surface by gradually shifting the phase of the sine wave. This creates a wave-like effect, simulating fluid movement inside the cylinder:

for k = 1:100
    [Xf, Yf, Zf] = cylinder(0.6 * (1 + 0.06 * sin(5 * t + 0.1 * k)));
    Zf = Zf * 3;
    set(fluid, 'XData', Xf, 'YData', Yf, 'ZData', Zf, 'CData', Zf);
    drawnow;
end

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For more information about the "cylinder" function, refer to the following MathWorks documentation link:

https://www.mathworks.com/help/matlab/ref/cylinder.html