Analysis of Variation of Velocity Along the Radius for Fully Developed Turbulent Flow Through Pipe Using Cfd

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Fig 5: Zoomed view of mesh.

After the analysis is done with selected model we get the variation along radius for fully developed turbulent flow and the parameters average shear stressin the pipe which has been used to validate the results from the base work.

III. RESULTS

The average shear stress in the pipe has been calculated using FEM solver ANSYS Fluent 14.5 for the velocities 0.01 m/s, 0.015 m/s, 0.02 m/s, 0.025 m/s, 0.03 m/s.

Table 3: Inlet conditions.

Inlet velocity m/s Reynolds number

0.010 10000

0.015 15000

0.020 20000

0.025 25000

0.030 30000

Fig 6: Velocity contour for Reynolds number 10000.

Fig 7: Velocity variation for Reynolds number10000.

Fig 8: Velocity contour for Reynolds number 15000.

Fig 9: Velocity variation for Reynolds number15000.

Fig 10: Velocity contour for Reynolds number 20000.

Fig 11: Velocity variation for Reynolds number 20000.

Fig 12: Velocity contour for Reynolds number 25000.

Fig 13: Velocity variation for Reynolds number 25000.

Fig 14: Velocity contour for Reynolds number 30000.

Fig 15: Velocity variation for Reynolds number 30000.

After performing the iteration for variousReynolds numbervalue of average shear stress and friction factor is obtained.

Shear stress: wall shear stress remains constant throughout the pipe during the flow for various Reynolds number.

Table3: Comparison of average shear stress obtained by simulation and reference work.

Average shear stress

( N/m2)

(Literature) Average shear stress

( N/m2)

(simulated) Difference

Reynolds number

0.00040 0.00040 0.00000 10000

0.00085 0.00080 0.00005 15000

0.00140 0.00140 0.00000 20000

0.00230 0.00200 0.00030 25000

0.00260 0.00280 -0.00020 30000

Fig 16: Average shear versus Reynolds number.

The result shows that the simulation is well validated with the reference work.

Friction factor: In fluid dynamics, the Darcy friction factor formulae are equations that allow the calculation of the Darcy friction factor, a dimensionless quantity used in the Darcy–Weisbach equation, for the description of friction losses in pipe flow as well as open-channel flow.

Fig 17: Friction Factor versus Average shear stress

It is evident from above plot as friction factor is varied with average shear stress it can be observed that friction factor decreases with increase in shear stress since Reynolds number is increasing so along the wall shear stress increases decreasing the friction factor.

IV. DISCUSSION

In this paper we’ve obtained friction factor, average shear stress, velocity variation along radius. It is clear that average shear stress increases with increase in Reynolds number or indirectly at the inlet velocity. Another parameter i.e. friction factor decreases with increase in inlet velocity, which means at high speed effect of friction is less. When friction factor and average shear stress is compared we came to know friction factor decreases with increase in average shear stress.

REFERENCES

[1]Ahsan, M., (2014), “Numerical analysis of friction factor for a fully developed turbulent flow using k-ε turbulence model with enhanced wall treatment”, Beni-Suef University Journal of Basic and Applied Sciences, pp. 1-9.

[2]Banfi, G.P., et al, (1981), “Velocity fluctuation enhancement in the transition to turbulence in a pipe”, Journal of Physics D: Applied Physics, Vol.14, pp. 625- 632.

[3] Bhandari, D., Singh, S., (2012), “Analysis of Fully Developed Turbulent Flow in a Pipe Using Computational Fluid Dynamics”, International Journal of Engineering Research & Technology, Vol. 1, Iss. 5, pp. 1-9.

[4] Ferrey, P., and Aupoix, B., (2006), “Behaviour of turbulence models near a turbulent/non turbulent interface revisited”, Journal of Heat and Fluid Flow, Vol. 27, pp. 831-837.

[5] Modi, P.N., and Seth, S.M., (2002), “Hydraulics And Fluid Mechanics Including Hydraulic Machines”, Ed. 14th, pp. 516-530.

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