MATLAB: Vpasolve function incorrect solution

matlab functionvpasolve

Hello
I am trying to solve this set of equations, however am getting incorrect solution:
syms Q1 Q2 f1 f2 Re1 Re2
eq1= Re1==(31.77E6)*Q1;
eq2= Re2==(15.88E6)*Q2;
eq3= 1/(f1^(1/2))==-1.8*log10(6.9/(Re1)+((1.125E-3)/3.7)^(1.11));
eq4= 1/(f2^(1/2))==-1.8*log10(6.9/(Re2)+((5.625E-4)/3.7)^(1.11));
eq5= 0.572==8*Q1*(1+sqrt(32*f1/f2))+(29.05E6)*f1*(Q1^2);
eq6= Q2==sqrt(32*f1/f2)*Q1;
S=vpasolve(eq1,eq2,eq3,eq4,eq5,eq6);
Matlab answer for f1 for example is 415671.45, however the correct answer should be approx 0.022. What am i doing wrong?

Best Answer

S1 = solve([eq1,eq2,eq5,eq6],[Q1,Q2,Re1,Re2]);
E2 = subs([eq3,eq4], S1);
sol1 = vpasolve(E2(1,:), [0 1; 0 1]);
The other branch, by solving E2(2,:), eventually gives up.
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