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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 1).
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Figure 2: The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 1).

Mentions: Figure 2a, b shows the R1 and R4 for Case 1. It is seen from Figure 2a, b that the coagulation of the small particles is the fastest. They become almost totally coagulated immediately even at the beginning. Comparatively, the coagulation of the larger particles takes place slowly and increasing steadily. However, the final level of coagulation of the larger particles is greater than that of smaller particles. In addition, the degree as well as the rapidity of the coagulation of the intermediate particles is intermediate between that of the smaller and the larger particles.


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 1).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: The flatness factor of the concentration distribution of nanoparticles. (The R1(a) and R4(b) for Case 1).
Mentions: Figure 2a, b shows the R1 and R4 for Case 1. It is seen from Figure 2a, b that the coagulation of the small particles is the fastest. They become almost totally coagulated immediately even at the beginning. Comparatively, the coagulation of the larger particles takes place slowly and increasing steadily. However, the final level of coagulation of the larger particles is greater than that of smaller particles. In addition, the degree as well as the rapidity of the coagulation of the intermediate particles is intermediate between that of the smaller and the larger particles.

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