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Numerical study of instability of nanofluids: the coagulation effect and sedimentation effect.

Ni Y, Fan J, Hu Y - Nanoscale Res Lett (2011)

Bottom Line: Three cases are simulated, focusing on the effects of the sizes, volume fraction, and ζ potentials of nano-particles on the formation of coagulation and sedimentation of nanofluids.The results indicate a superposition of coagulation and sedimentation effect of small nano-particles.Moreover, it is stable of nanofluids with the volume fraction of particles below the limit of "resolution" of the fluids.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, P, R, China. fanjr@zju.edu.cn.

ABSTRACT
This study is a numerical study on the coagulation as well as the sedimentation effect of nanofluids using the Brownian dynamics method. Three cases are simulated, focusing on the effects of the sizes, volume fraction, and ζ potentials of nano-particles on the formation of coagulation and sedimentation of nanofluids. The rms fluctuation of the particle number concentration, as well as the flatness factor of it, is employed to study the formation and variation of the coagulation process. The results indicate a superposition of coagulation and sedimentation effect of small nano-particles. Moreover, it is stable of nanofluids with the volume fraction of particles below the limit of "resolution" of the fluids. In addition, the effect of ζ potentials is against the formation of coagulation and positive to the stability of nanofluids.

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Related in: MedlinePlus

Snapshots of simulation results. (Case 3 for ζ = 0.01 eV (a-d) and ζ = 0.05 eV (e-h) at t = 0, 5, 10, and 50 μs, respectively).
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Figure 5: Snapshots of simulation results. (Case 3 for ζ = 0.01 eV (a-d) and ζ = 0.05 eV (e-h) at t = 0, 5, 10, and 50 μs, respectively).

Mentions: Comparing with Figure 1e, f, g, h, it is seen that the degree of coagulation with ζ = 0.01 eV is attenuated (Figure 5a, b, c, d), and it almost disappears with ζ = 0.05 eV (Figure 5e, f, g, h). It indicates that the repulsive effect induced by the ζ potentials is beneficial to the stability of nanofluids, since it acts against the coagulation process.


Numerical study of instability of nanofluids: the coagulation effect and sedimentation effect.

Ni Y, Fan J, Hu Y - Nanoscale Res Lett (2011)

Snapshots of simulation results. (Case 3 for ζ = 0.01 eV (a-d) and ζ = 0.05 eV (e-h) at t = 0, 5, 10, and 50 μs, respectively).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211237&req=5

Figure 5: Snapshots of simulation results. (Case 3 for ζ = 0.01 eV (a-d) and ζ = 0.05 eV (e-h) at t = 0, 5, 10, and 50 μs, respectively).
Mentions: Comparing with Figure 1e, f, g, h, it is seen that the degree of coagulation with ζ = 0.01 eV is attenuated (Figure 5a, b, c, d), and it almost disappears with ζ = 0.05 eV (Figure 5e, f, g, h). It indicates that the repulsive effect induced by the ζ potentials is beneficial to the stability of nanofluids, since it acts against the coagulation process.

Bottom Line: Three cases are simulated, focusing on the effects of the sizes, volume fraction, and ζ potentials of nano-particles on the formation of coagulation and sedimentation of nanofluids.The results indicate a superposition of coagulation and sedimentation effect of small nano-particles.Moreover, it is stable of nanofluids with the volume fraction of particles below the limit of "resolution" of the fluids.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, P, R, China. fanjr@zju.edu.cn.

ABSTRACT
This study is a numerical study on the coagulation as well as the sedimentation effect of nanofluids using the Brownian dynamics method. Three cases are simulated, focusing on the effects of the sizes, volume fraction, and ζ potentials of nano-particles on the formation of coagulation and sedimentation of nanofluids. The rms fluctuation of the particle number concentration, as well as the flatness factor of it, is employed to study the formation and variation of the coagulation process. The results indicate a superposition of coagulation and sedimentation effect of small nano-particles. Moreover, it is stable of nanofluids with the volume fraction of particles below the limit of "resolution" of the fluids. In addition, the effect of ζ potentials is against the formation of coagulation and positive to the stability of nanofluids.

No MeSH data available.


Related in: MedlinePlus