fill the 2D plot

Hello

I have a plot of a two-layer fluids. I want to fill the plots with different color (lower layer red- upper layer blue)

I dont know how to use 'fill' command to do this.

would you please help me?

[Adam Danz]

Here's your figure. Which regions do you want to fill?

[sepideh]

Thanks for your attention, I got the results

Answer 1

[Sulaymon Eshkabilov]

An easiest way would be using area() instead of plot() and patch():

v= 0.6;
r=2;
gam1= (1-v)/((r*v)-1)    %for constant depth (F*=gam1=2) .here  we should put a smaller gamma hence i put 1.15

gam1 = 2.0000

% TRY DIFFERENT NUMBER OF GAM RESULT IN STRANGE BEHAVIOUR 
gam=1.44;            
xil=(9^(2/3)*((1+gam)^(2/3)))^(1/2)

xil = 2.8003

xiu= ((v*xil^2)+((9^(2/3))*(v^(2/3))*(gam^(2/3))*((r-1)*(2/3))*((1-v)^(1/3))))^(1/2)   

xiu = 2.5755

xi_star=   ( ((xiu^2)-v*xil^2)/(1-v)) ^(1/2);
xi=linspace(0,xi_star,1000);
fl=@(xi) ((xiu^2-(v*xil^2))/(6*v*(r-1)))+(((v-1)*xi.^2)/(6*v*(r-1)));
fu=@(xi) (((r*v*xil^2)-xiu^2)/(6*v*(r-1)))+(((1-r*v)*xi.^2)/(6*v*(r-1)))+((xiu^2-(v*xil^2))/(6*v*(r-1)))+(((v-1)*xi.^2)/(6*v*(r-1)));
figure(2)
hold on 
B =area(xi, fu(xi));
B.FaceColor = [0 0 1];
B.EdgeColor = [0 0 1];
B.LineWidth = 2;

hold on
xii=linspace(xi_star,xil);
fll=@(xii) ((xil^2-xii.^2)./(6));
C =area(xii, fll(xii));
C.FaceColor = [0 0 1];
C.EdgeColor = [0 0 1];
C.LineWidth = 2;
A =area(xi, fl(xi));
A.FaceColor = [1 0 0];
A.EdgeColor = [1 0 0];
A.LineWidth = 2;

[sepideh]

Thats great !

thank you

[Sulaymon Eshkabilov]

Acceptable answer :)

[sepideh]

sure, I forgot. sorry

[Sulaymon Eshkabilov]

All the best!