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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

The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 2).
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Figure 4: The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 2).

Mentions: In addition, Figure 4a, b shows the R1 and R4 of Case 2. It is seen from Figure 4 that the R1 and R4 for np = 400 are always relatively of small value, indicating a stable status almost without coagulation and sedimentation, although R4 is slightly fluctuated when t < 0.06. Moreover, compared to np = 1200, it is seen that the concentration fluctuation R1 and flatness factor of concentration R4 for np = 400 are relatively of lower values. It validates the conclusions derived from the observation of Figure 3a, b, c, d, in comparison with Figure 1e, 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)

The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 2).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 2).
Mentions: In addition, Figure 4a, b shows the R1 and R4 of Case 2. It is seen from Figure 4 that the R1 and R4 for np = 400 are always relatively of small value, indicating a stable status almost without coagulation and sedimentation, although R4 is slightly fluctuated when t < 0.06. Moreover, compared to np = 1200, it is seen that the concentration fluctuation R1 and flatness factor of concentration R4 for np = 400 are relatively of lower values. It validates the conclusions derived from the observation of Figure 3a, b, c, d, in comparison with Figure 1e, 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