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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.

No MeSH data available.


Related in: MedlinePlus

Snapshots of simulation results. (Case 2 for np = 400 (a-d) and np = 4200 (e-h) at t = 0, 5, 10, and 50 μs respectively).
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Figure 3: Snapshots of simulation results. (Case 2 for np = 400 (a-d) and np = 4200 (e-h) at t = 0, 5, 10, and 50 μs respectively).

Mentions: For example, Figure 3a, b, c, d shows one of the results of Case 2 where only np = 400 particles are simulated. Compared to Figure 1a, b, c, d, it is seen that the coagulation does not takes place at t = 50 μs. It says that the coagulation is to be regarded appropriately as a process with an excess of particle content. When the particle numbers go beyond the superior limit of the resolvent, then the coagulation will certainly take place. Thus, when the np = 4200 particles are simulated, more intensive coagulations are observed correspondingly (Figure 3e, f, g, h).


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 2 for np = 400 (a-d) and np = 4200 (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 3: Snapshots of simulation results. (Case 2 for np = 400 (a-d) and np = 4200 (e-h) at t = 0, 5, 10, and 50 μs respectively).
Mentions: For example, Figure 3a, b, c, d shows one of the results of Case 2 where only np = 400 particles are simulated. Compared to Figure 1a, b, c, d, it is seen that the coagulation does not takes place at t = 50 μs. It says that the coagulation is to be regarded appropriately as a process with an excess of particle content. When the particle numbers go beyond the superior limit of the resolvent, then the coagulation will certainly take place. Thus, when the np = 4200 particles are simulated, more intensive coagulations are observed correspondingly (Figure 3e, f, g, h).

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