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2. Viscosity Measurements on Colloidal Dispersions (Nanofluids) for Heat Transfer Applications

Author

Venerus David C., Buongiorno Jacopo, Christianson Rebecca, Townsend Jessica, Bang In Cheol, Chen Gang, Chung Sung Jae, Chyu Minking, Chen Haisheng, Ding Yulong, Dubois Frank, Dzido Grzegorz, Funfschilling Denis, Galand Quentin, Gao Jinwei, Hong Haiping, Horton Mark, Hu Linwen, Iorio Carlo S., Jarzebski Andrzej B., Jiang Yiran, Kabelac Stephan, Kedzierski Mark A., Kim Chongyoup, Kim Ji-Hyun, Kim Sukwon, McKrell Thomas, Ni Rui, Philip John, Prabhat Naveen, Song Pengxiang, Van Vaerenbergh Stefan, Wen Dongsheng, Witharana Sanjeeva, Zhao Xiao-Zheng, and Zhou Sheng-Qi

Subjects
nanofluids, colloidal dispersion, viscosity, thermal conductivity, Materials of engineering and construction. Mechanics of materials, TA401-492
Abstract

This article reports viscosity data on a series of colloidal dispersions collected as part of the International Nanofluid Property Benchmark Exercise (INPBE). Data are reported for seven different fluids that include dispersions of metal-oxide nanoparticles in water, and in synthetic oil. These fluids, which are also referred to as ‘nanofluids,’ are currently being researched for their potential to function as heat transfer fluids. In a recently published paper from the INPBE study, thermal conductivity data from more than 30 laboratories around the world were reported and analyzed. Here, we examine the influence of particle shape and concentration on the viscosity of these same nanofluids and compare data to predictions from classical theories on suspension rheology.

Published
2010
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5. Process of Forensic Medicine in DNA Identification of Aged Human Remains

Author

Lu CHEN, Zhe ZHOU, Sheng-qi WANG

Subjects
forensic genetics, individual identification, aged skeleton, tooth, degraded, high throughput sequencing, review, Medicine
Abstract

Skeleton and teeth are important biological samples. Due to their special structure and strong ability to resist degradation, they are ideal biological materials to retain DNA under natural condition. In many cases, such as historical figure identification, aged skeleton and teeth are usually the only biological samples. However, their DNA is in a state of trace, damage and degradation to different degrees, which requires special experimental treatment to achieve identification. This paper reviews the sample selection, DNA extraction, DNA enrichment and analysis approaches based on relevant research reports in recent years, aiming to promote the further development and improvement of the aged skeleton and teeth identification system.

Published
2023
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6. Existence of Bolgiano–Obukhov scaling in the bottom ocean?

Author

Huang, Peng-Qi, Guo, Shuang-Xi, Zhou, Sheng-Qi, Cen, Xian-Rong, Qu, Ling, Zhu, Ming-Quan, and Lu, Yuan-Zheng

Subjects
TURBULENT mixing, BOUNDARY layer (Aerodynamics), ATMOSPHERIC layers, MIXING height (Atmospheric chemistry), OCEAN bottom, STRATIFIED flow, INTERNAL waves
Abstract

The seminal Bolgiano–Obukhov (BO) theory established the fundamental framework for turbulent mixing and energy transfer in stably stratified fluids. However, the presence of BO scalings remains debatable despite their being observed in stably stratified atmospheric layers and convective turbulence. In this study, we performed precise temperature measurements with 51 high-resolution loggers above the seafloor for 46 h on the continental shelf of the northern South China Sea. The temperature observation exhibits three layers with increasing distance from the seafloor: the bottom mixed layer (BML), the mixing zone and the internal wave zone. A BO-like scaling $\alpha =-1.34\pm 0.10$ is observed in the temperature spectrum when the BML is in a weakly stable stratified ($N\sim 0.0018$ rad s $^{-1}$) and strongly sheared ($Ri\sim 0.0027$) condition, whereas in the unstably stratified convective turbulence of the BML, the scaling $\alpha =-1.76\pm 0.10$ clearly deviated from the BO theory but approached the classical $-$ 5/3 scaling in isotropic turbulence. This suggests that the convective turbulence is not the promise of BO scaling. In the mixing zone, where internal waves alternately interact with the BML, the scaling follows the Kolmogorov scaling. In the internal wave zone, the scaling $\alpha =-2.12 \pm 0.15$ is observed in the turbulence range and possible mechanisms are provided. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Diffusive-Convection Staircase Merger Events Mediated by Subsurface Eddies in the Canada Basin

Author

Chai, Xia, Zhou, Sheng-Qi, Wang, Yan, Chai, Xia, Zhou, Sheng-Qi, and Wang, Yan

Abstract

Diffusive-convection (DC) staircases, characterized by interleaving well-mixed layers and high-gradient interfaces of thermohaline properties, are commonly observed in the Canada Basin, Arctic. Previous studies suggested a quasi-steady state of the thermohaline structures of these staircases. In this work, we employ mooring and Ice-Tethered Profiler (ITP) data to show emergent merger events of staircases mediated by subsurface eddies with warm cores located at 300-500 m depths in 2005, 2007 and 2009. Two types of merger events, the B-merger (resulting from strengthening of stronger interfaces at the expense of weaker ones) and the H-merger (produced by vertical drift and collision of staircase interfaces), are documented during the passage of subsurface eddies. The merging staircases are located at 320-450 m depths, with layers of up to 70 m thick and high-gradient interfaces thinner than 5 m. Mooring measurements reveal the emergence of staircase mergers associated with a background Richardson number dropping from a typical magnitude of O(100) $\textbackslash{}mathcal{O}(100)$-O(10) $\textbackslash{}mathcal{O}(10)$ to O(0.1) $\textbackslash{}mathcal{O}(0.1)$, indicating the persistence of DC staircases in the presence of strong shears. In parallel, ITP data suggest the formation of B-mergers (H-mergers) to be favored within the eddy core (flank). The vertical heat fluxes associated with the B-merger (H-merger) staircases are estimated to be similar to 3 W/m2 (similar to 1.5 W/m2), which substantially exceed the typical staircase-driven heat fluxes of O(0.1) $\textbackslash{}mathcal{O}(0.1)$ W/m2. These observations imply the significance of subsurface eddies in shaping the halocline structures and thus the vertical heat fluxes in the Arctic Ocean, particularly in a warming climate. In the Arctic Ocean, warm waters derived from the Atlantic Ocean lie beneath surface cold waters, and store sufficient heat capable of melting the Arctic ice cover. Residing between the

Published
2024

8. Flow reversals in thermally driven turbulence

Author

Sugiyama, Kazuyasu, Ni, Rui, Stevens, Richard J. A. M., Chan, Tak Shing, Zhou, Sheng-Qi, Xi, Heng-Dong, Sun, Chao, Grossmann, Siegfried, Xia, Ke-Qing, and Lohse, Detlef

Subjects
Physics - Fluid Dynamics
Abstract

We analyze the reversals of the large scale flow in Rayleigh-B\'enard convection both through particle image velocimetry flow visualization and direct numerical simulations (DNS) of the underlying Boussinesq equations in a (quasi) two-dimensional, rectangular geometry of aspect ratio 1. For medium Prandtl number there is a diagonal large scale convection roll and two smaller secondary rolls in the two remaining corners diagonally opposing each other. These corner flow rolls play a crucial role for the large scale wind reversal: They grow in kinetic energy and thus also in size thanks to plume detachments from the boundary layers up to the time that they take over the main, large scale diagonal flow, thus leading to reversal. Based on this mechanism we identify a typical time scale for the reversals. We map out the Rayleigh number vs Prandtl number phase space and find that the occurrence of reversals very sensitively depends on these parameters., Comment: 4 pages, 4 figures

Published
2011
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11. Oscillations of the large-scale circulation in turbulent Rayleigh-B\'{e}nard convection: the off-center mode and its relationship with the torsional mode

Author

Zhou, Quan, Xi, Heng-Dong, Zhou, Sheng-Qi, Sun, Chao, and Xia, Ke-Qing

Subjects
Physics - Fluid Dynamics
Abstract

We report an experimental study of the large-scale circulation (LSC) in a turbulent Rayleigh-B\'{e}nard convection cell with aspect ratio unity. The temperature-extremum-extraction (TEE) method for obtaining the dynamic information of the LSC is presented. With this method, the azimuthal angular positions of the hot ascending and cold descending flows along the sidewall are identified from the measured instantaneous azimuthal temperature profile. The motion of the LSC is then decomposed into two different modes: the azimuthal mode and the translational or off-center mode. Comparing to the previous sinusoidal-fitting (SF) method, it is found that both methods give the same information about the azimuthal motion of the LSC, but the TEE method in addition can provide information about the off-center motion of the LSC, which is found to oscillate time-periodically around the cell's central vertical axis with an amplitude being nearly independent of the turbulent intensity. It is further found that the azimuthal angular positions of the hot ascending flow near the bottom plate and the cold descending flow near the top plate oscillate periodically out of phase by $\pi$, leading to the torsional mode of the LSC. These oscillations are then propagated vertically along the sidewall by the hot ascending and cold descending fluids. When they reach the mid-height plane, the azimuthal positions of the hottest and coldest fluids again oscillate out of phase by $\pi$. It is this out-of-phase horizontal positional oscillation of the hottest and coldest fluids at the same horizontal plane that produces the off-center oscillation of the LSC. A direct velocity measurement further confirms the existence of the bulk off-center mode of the flow field near cell center., Comment: 13 pages, 14 figures, the paper has been submitted to J. Fluid Mech

Published
2008
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12. Origin of the Temperature Oscillation in Turbulent Thermal Convection

Author

Xi, Heng-Dong, Zhou, Sheng-Qi, Zhou, Quan, Chan, Tak-Shing, and Xia, Ke-Qing

Subjects
Physics - Fluid Dynamics
Abstract

We report an experimental study of the three-dimensional spatial structure of the low frequency temperature oscillations in a cylindrical Rayleigh-B\'{e}nard convection cell. It is found that thermal plumes are not emitted periodically, but randomly and continuously, from the top and bottom plates. We further found that the oscillation of the temperature field does not originate from the boundary layers, but rather is a result of the horizontal motion of the hot ascending and cold descending fluids being modulated by the twisting and sloshing motion of the bulk flow field., Comment: 5 figures

Published
2008
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13. Measured oscillations of the velocity and temperature fields in turbulent Rayleigh-B\'{e}nard convection in a rectangular cell

Author

Zhou, Sheng-Qi, Sun, Chao, and Xia, Ke-Qing

Subjects
Physics - Fluid Dynamics
Abstract

Temperature and velocity oscillations have been found in a rectangular Rayleigh-B\'{e}nard convection cell, in which one large scale convection roll exists. At $Ra=8.9 \times 10^{11}$ and $Pr=4$, temperature oscillation can be observed in most part of the system and the oscillation period remains almost constant, $t_T = 74 \pm 2$ seconds. Velocity oscillation can only be found in its horizontal component, $v_y$ (perpendicular to large scale circulation plane), near the cell sidewall, its oscillation period is also constant, $t_T = 65 \pm 2$ seconds, at these positions. Temperature and velocity oscillations have different Ra dependence, which are respectively indicated by Peclect number $Pe_T = 0.55Ra^{0.47}$ and $Pe_v = 0.28Ra^{0.50}$ . In comparison to the case of cylindrical cell, we find that the velocity oscillation is affected by the system geometry., Comment: 6 pages, 6 figures. submitted to PRE

Published
2007
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14. Fluctuations of a homeotropically aligned nematic liquid crystal in the presence of an applied voltage

Author

Zhou, Sheng-Qi and Ahlers, Guenter

Subjects
Nonlinear Sciences - Pattern Formation and Solitons
Abstract

We determined the refractive-index structure-factor $S_n(\bf k)$ from shadowgraphs of fluctuations in a layer of a homeotropically aligned nematic liquid crystal with negative dielectric anisotropy in the presence of an ac voltage of amplitude $V_0$ applied orthogonal to the layer. $S_n(\bf k)$ had rotational symmetry. Its integral $P(V_0)$ and amplitude $B(V_0)$ increased smoothly through the Fr\'eedericksz transition at $V_0 = V_F$. Its inverse width $\xi(V_0)$ and its relaxation rate $\Gamma_0(V_0)$ had cusps but remained finite at $V_F$. The results are inconsistent with the critical mode at a second-order phase transition., Comment: 4 pages, 5 figures

Published
2004

21. Similarity of the turbulent kinetic energy dissipation rate distribution in the upper mixed layer of the tropical Indian Ocean

Author

Cen, Xian-Rong, Guo, Shuang-Xi, Wang, Yan, Zhou, Sheng-Qi, Cen, Xian-Rong, Guo, Shuang-Xi, Wang, Yan, and Zhou, Sheng-Qi

Abstract

Turbulence within the upper ocean mixed layer plays a key role in various physical, biological, and chemical processes. Between September and November 2011, a dataset of 570 vertical profiles of the turbulent kinetic energy (TKE) dissipation rate, as well as conventional hydrological and meteorological data, were collected in the upper layer of the tropical Indian Ocean. These data were used to statistically analyze the vertical distribution of the TKE dissipation rate in the mixed layer. The arithmetic-mean method made the statistical TKE dissipation rate profile more scattered than the median and geometric-mean methods. The statistical TKE dissipation rate were respectively scaled by the surface buoyancy flux and the TKE dissipation rate at the mixed-layer base. It was found that the TKE dissipation rate scaled by that at the mixed-layer base exhibited better similarity characteristics than that scaled by the surface buoyancy flux, whether the stability parameter D/\L-MO\ was greater or less than 10, indicating that the TKE dissipation rate at the mixed-layer base is a better characteristic scaling parameter for reflecting the intrinsic structure of the TKE dissipation rate in the mixed layer, where D and L-MO are respectively the mixed-layer thickness and the Monin-Obukhov length scale. The parameterization of the TKE dissipation rate at the mixed-layer base on the shear-driven dissipation rate and the surface buoyancy flux was further explored. It was found that the TKE dissipation rate at the mixed-layer base could be well fitted by a linear combination of three terms: the wind-shear-driven dissipation rate, the surface buoyancy flux, and a simple nonlinear coupling term of these two .

Published
2022

33. Effects of shear rate and temperature on viscosity of alumina polyalphaolefins nanofluids.

Author

Zhou, Sheng-Qi, Ni, Rui, and Funfschilling, Denis

Subjects
*NANOFLUIDS, *VISCOSITY, *ALUMINUM oxide, *NEWTONIAN fluids, *NANOPARTICLES
Abstract

In this paper, the shear rate and temperature dependencies of viscosity of alumina nanofluids have been investigated experimentally. The alumina nanofluids are suspensions of alumina nanospheres or nanorods in polyalphaolefins (PAO) lubricant. The base fluid PAO has a Newtonian behavior. To the first approximation, nanofluids of volume fractions [lowercase_phi_synonym]=1% and 3% nanospheres as well as nanofluid of [lowercase_phi_synonym]=1% nanorods can be considered as Newtonian fluids because their viscosity shows very weak shear rate dependence. However, our measurement clearly indicates that these nanofluids demonstrate certain non-Newtonian feature due to the addition of nanoparticles. Moreover, the relative viscosity (the ratio of viscosity of nanofluid to that of PAO) of these nanofluids has been measured to be independent of temperature. Nanofluid of a higher volume fraction [lowercase_phi_synonym]=3% nanorods has an apparent non-Newtonian shear thinning viscosity and a strong temperature dependence of its relative viscosity. By reviewing the previous studies, the approximation that the viscosity is Newtonian and the relative viscosity is independent of temperature seem to hold for most nanofluids of low volume fraction [lowercase_phi_synonym] and low aspect ratio nanoparticles. [ABSTRACT FROM AUTHOR]

Published
2010
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42. Parametric identification study of an active engine mount: Combination of finite element analysis and experiment.

Author

Guo, Rong, Wei, Xiao-kang, Zhou, Sheng-qi, and Gao, Jun

Abstract

An active engine mount (AEM) is an effective technology to improve a vehicle's noise, vibration, and harshness performance. This paper mainly focuses on the combination experiment and finite element analysis (FEA) for parameter identification of AEMs. Notably, a novel test rig is designed to identify all specific parameters involved in the AEM. Firstly, the static and dynamic stiffness of the main rubber spring are calculated based on structure FEA method. The equivalent piston area and upper chamber volumetric stiffness are also estimated through fluid–structure interaction analysis. Inertia track parameters, involving inertia and linear and nonlinear resistance of the fluid, are identified by a simplified fluid model. These common hydraulic engine mount parameters are all experimentally validated through the original test rig. Besides, the particular components of the electromagnetic AEM, namely actuator parameters, are further estimated by experimental identification utilizing the experimental apparatus. The novel test bench, which exhibited high accuracy, good tightness, and strong versatility, not only simplifies the structure and process of identification plant for passive engine mount parameters, but accommodates the particular AEM ones. The combination method assimilates both the efficiency of FEA and the accuracy of experiment, facilitating the structure design and renovation of AEMs. [ABSTRACT FROM AUTHOR]

Published
2019
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47. Flow Reversals in Thermally Driven Turbulence

Author

Sugiyama, Kazuyasu, primary, Ni, Rui, additional, Stevens, Richard J. A. M., additional, Chan, Tak Shing, additional, Zhou, Sheng-Qi, additional, Xi, Heng-Dong, additional, Sun, Chao, additional, Grossmann, Siegfried, additional, Xia, Ke-Qing, additional, and Lohse, Detlef, additional

Published
2010
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48. A benchmark study on the thermal conductivity of nanofluids

Author

Buongiorno, Jacopo, primary, Venerus, David C., additional, Prabhat, Naveen, additional, McKrell, Thomas, additional, Townsend, Jessica, additional, Christianson, Rebecca, additional, Tolmachev, Yuriy V., additional, Keblinski, Pawel, additional, Hu, Lin-wen, additional, Alvarado, Jorge L., additional, Bang, In Cheol, additional, Bishnoi, Sandra W., additional, Bonetti, Marco, additional, Botz, Frank, additional, Cecere, Anselmo, additional, Chang, Yun, additional, Chen, Gang, additional, Chen, Haisheng, additional, Chung, Sung Jae, additional, Chyu, Minking K., additional, Das, Sarit K., additional, Di Paola, Roberto, additional, Ding, Yulong, additional, Dubois, Frank, additional, Dzido, Grzegorz, additional, Eapen, Jacob, additional, Escher, Werner, additional, Funfschilling, Denis, additional, Galand, Quentin, additional, Gao, Jinwei, additional, Gharagozloo, Patricia E., additional, Goodson, Kenneth E., additional, Gutierrez, Jorge Gustavo, additional, Hong, Haiping, additional, Horton, Mark, additional, Hwang, Kyo Sik, additional, Iorio, Carlo S., additional, Jang, Seok Pil, additional, Jarzebski, Andrzej B., additional, Jiang, Yiran, additional, Jin, Liwen, additional, Kabelac, Stephan, additional, Kamath, Aravind, additional, Kedzierski, Mark A., additional, Kieng, Lim Geok, additional, Kim, Chongyoup, additional, Kim, Ji-Hyun, additional, Kim, Seokwon, additional, Lee, Seung Hyun, additional, Leong, Kai Choong, additional, Manna, Indranil, additional, Michel, Bruno, additional, Ni, Rui, additional, Patel, Hrishikesh E., additional, Philip, John, additional, Poulikakos, Dimos, additional, Reynaud, Cecile, additional, Savino, Raffaele, additional, Singh, Pawan K., additional, Song, Pengxiang, additional, Sundararajan, Thirumalachari, additional, Timofeeva, Elena, additional, Tritcak, Todd, additional, Turanov, Aleksandr N., additional, Van Vaerenbergh, Stefan, additional, Wen, Dongsheng, additional, Witharana, Sanjeeva, additional, Yang, Chun, additional, Yeh, Wei-Hsun, additional, Zhao, Xiao-Zheng, additional, and Zhou, Sheng-Qi, additional

Published
2009
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