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Element matrix equation,
[K]e=1Re[1−1−11], where, Re=128μheπd4e
Forelement1,d=15mm,he=7.5m
Re=128∗8∗10−4∗7.5π(0.015)4=4828878.87
[K]1=10−7[2.07−2.07−2.072.07]
Forelement2,d=20mm,he=10m
Re=128∗8∗10−4∗10π(0.02)4=2037183.27
[K]2=10−7[4.91−4.91−4.914.91]
Forelement3,d=12.5mm,he=10m
Re=128∗8∗10−4∗10π(0.0125)4=13350884.29
[K]3=10−7[0.75−0.75−0.750.75]
Forelement4,d=7.5mm,he=7.5m
Re=128∗8∗10−4∗7.5π(0.0075)4=24446199.26
[K]4=10−7[0.41−0.41−0.410.41]
c) Element Stiffness matrix
[K]=10−7[2.07+4.91−2.07−4.910−2.072.07+0.750−0.75−4.9104.91+0.41−0.410−0.75−0.410.75+0.41]
d) Global Stiffness Matrix Equation,
[K]{P}e={Q}
∴10−7[6.98−2.07−4.910−2.072.820−0.75−4.9105.32−0.410−0.75−0.411.16]{P1P2P3P4}={Q1Q2Q3Q4}
e) Imposing boundary condition,
Q1=0.16∗10−3m3/sec,P4=0,Q3=0
Q2=0
f) Frame the equation,
10−7(6.98P1−2.07P2−4.91P3)=0.16∗10−3 -(1)
10−7(−2.07P1+2.82P2)=0 -(2)
10−7(−4.91P1+5.32P3)=0 -(3)
10−7(−0.75P2−0.41P3)=Q4 -(4)
Solving equation (2) and (3) we get,
∴P1=1722.4N/m2P2=1264.32N/m2P3=1589.662N/m2
Substituting in equation (4), we get,
Q4=−1600
Flow rate in pipe,
Q1=P1−P2R1=1722.4−1264.324828878.87∗1000
∴Q1=0.09486lit/sec
Q2=P1−P3R2=1722.4−1589.6622037183.27∗1000
∴Q2=0.06516lit/sec
Q3=P2−P4R3=1264.32−013350884.29∗1000
∴Q3=0.0947lit/sec
Q4=P3−P4R4=1589.662−024446199.26∗1000
∴Q4=0.06502lit/sec
Check,
Q1+Q2≈0.16002lit/sec
Q3+Q4≈0.15972lit/sec
Also,
Q1≈Q3
Q2≈Q4 - Hence Verified.