Journal of Pure and Applied Ultrasonics

Vimal Pandey ¹, Giridhar Mishra ², Meher Wan ³, Devraj Singh ², A. K. Tiwari ⁴, R. R. Yadav ³, Bharat Mishra ⁵

Affiliations
1 Mahatma Gandhi Chitrakoot Gramodaya Vishwavidyalaya, Satna-485334, IN
2 Amity School of Engineering and Technology (Affiliated to GGSIP University), Bijwasan, New Delhi-110061, IN
3 University of Allahabad, Allahabad-211002, IN
4 B.S.N.V.P.G. College (University of Lucknow) Charbagh, Lucknow-226001, IN
5 Mahatma Gandhi Chitrakoot Gramoday Vishwavidyalaya, Satna-485334, IN

Abstract

Nanofluids have unique features different from conventional solid-liquid mixtures which have millimeter or micrometer sized particles dispersed in some base fluid. Due to their excellent characteristics, these new types of fluids have attracted wide interest in recent years. It is found that nanofluids have significantly higher thermal conductivity than the base fluids. In this work we focus on the ultrasonic and thermal properties of nanofluids. Nanofluids containing copper nanoparticles with base fluid polyvinyl alcohol (PVA) have been developed in our laboratory. These nanofluids are characterized by UV-Visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Temperature dependent ultrasonic velocity and ultrasonic attenuation measurements are performed for different concentration of the copper nanoparticles in the PVA. Hot Disk Thermal Constant Analyser is used for the measurement of the thermal conductivity of synthesized nanofluids. Experimental results show that the thermal conductivities of the nanofluids are higher than that of base fluid PVA. The obtained results were analyzed taking into account the ultrasonic and thermal behavior of matrix and particles. Possible mechanism for the enhancement of thermal conductivity of the nanofluids using theoretical model is also discussed.

Keywords

Nanofluids, Ultrasonic Properties, Enhanced Heat Transfer, Effective Thermal Conductivity, Brownian Motion.

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Giridhar Mishra ¹, R. R. Yadav ¹, Baldev Raj ², T. Jayakumar ²

Affiliations
1 Physics Department, University of Allahabad, Allahabad-211002, IN
2 Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, IN

Abstract

The single crystal higher order elastic constants of Ni-Al-Cr ternary alloy at different temperatures have been calculated with the help of interaction potential model. Ultrasonic attenuation in the ternary alloy is determined using higher order elastic constants. Other ultrasonic parameters such as Gruneisen numbers, acoustic coupling constants and acoustical anisotropy have been also calculated to discuss the ultrasonic properties of the ternary alloys. The ultrasonic wave propagation behavior at different temperatures for Ni-Al-Cr alloy have been investigated and correlated with respect to the microstructural phenomena during the wave propagation and thermal behavior of the ternary alloy. An ultrasonic mechanism has been developed to correlate the temperature dependent ultrasonic properties with the thermophysical properties particularly the thermal conductivity of the alloy. The results are compared with earlier studies of the elastic constants and are found to be in good agreement. We find that the thermal conductivity of Ni-Al-Cr alloy plays important role in the ultrasonic wave propagation behavior inside the alloy.

Keywords

Ternary Alloy, Elastic Constants, Ultrasonic Attenuation, Thermal Properties.

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Giridhar Mishra ¹, R. R. Yadav ¹, S. K. Kor ¹

Affiliations
1 Physics Department, University of Allahabad, Allahabad-211002, IN

Abstract

In the present work, the characterization of a calamitic liquid crystal mixture-sodium lauryl sulphate (SLS)/decanol/water-has been reported using ultrasonic velocity and absorption measurements as a function of temperature and concentration. The experimental tools used were, ultrasonic interferometry for the velocity and pulse-echo technique for the absorption measurements. The results are discussed in terms of the temperature and concentration dependent lyotropic liquid crystal formed in the material system.

Keywords

Ultrasonic Velocity, Ultrasonic Absorption, Lyotropic Liquid Crystals, Pulse-Echo Technique.

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Vimal Pandey ¹, S. K. Verma ², R. R. Yadav ²

Affiliations
1 Department of Physical Sciences, Mahatma Gandhi Chitrakoot Gramodaya Vishwavidyalaya, Chitrakoot, Satna (M.P.), IN
2 Department of Physics, University of Allahabad, Allahabad-211002, IN

Abstract

Study of nanofluids is important for different types of heat transfer management systems. Three different samples of CuO nanoparticles-PVA nanofluids are prepared through the chemical routes using ultrasonication. Temperature dependent ultrasonic velocity in the samples is measured and the behavior is correlated to extract the important information about thermal conduction at different temperatures. The results are applicable for the heat management in microelectronic industries.

Keywords

Nanofluid, Ultrasonic Attenuation, Ultrasonic Velocity.

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R. R. Yadav ¹, D. K. Pandey ¹

Affiliations
1 Physics Department, Allahabad University, Allahabad-211002, IN

Abstract

The ultrasonic attenuation due to phonon-phonon interaction has been evaluated in β-phase NiAl in high temperature interval 300-1400K along the crystallographic directions <100>, <110> and <111> for longitudinal and shear waves. For this evaluation we have calculated second and third order elastic constants (SOEC and TOEC) at the different temperatures using only two basic parameters. Ultrasonic velocities and Non-linearity parameters are calculated using the elastic constants. Structural stability, abrupt change in ductility, disordering at T_C may be predicted on the basis of temperature variation of the elastic constants and the ultrasonic attenuation.

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Devraj Singh ¹, R. R. Yadav ¹

Affiliations
1 Department of Physics, University of Allahabad, Allahabad-211002, IN

Abstract

In this paper ultrasonic absorption and other associated parameters have been evaluated in AgCl, LiF and MnO along different directions as a function of higher temperatures. We have also calculated the second and third order elastic constants of these materials for the evaluations. The results are compared with experimental values. It is concluded that the lattice thermal conductivity played an important role in temperature dependence of the ultrasonic absorption in these dielectrics.

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Shakti Pratap Singh ¹, P. K. Yadawa ², P. K. Dhawan ², A. K. Verma ¹, R. R. Yadav ¹

Affiliations
1 Department of Physics, University of Allahabad, Allahabad-211002, IN
2 Department of Physics, Prof. Rajendra Singh (Rajju Bhaiya) Institute of Physical Sciences for Study and Research, V.B.S. Purvanchal University, Jaunpur- 222003, IN

Abstract

The ultrasonic attenuation and velocities following electron viscosity mechanism has been computed in semi-metallic, superconducting single crystal Iron Selenide(FeSe) in low temperatures 10-70K. We have also calculated the electron-viscosity at different low temperature needed for the calculation of ultrasonic attenuation. The behaviour of ultrasonic attenuation is quite similar to its inverse electrical resistivity. The ultrasonic attenuation due to electron viscosity mechanism is most significant at 15 K. Computed results of ultrasonic parameters have been discussed.

Keywords

Elastic Constant, Electrical Resistivity, Superconductor, Ultrasonic Attenuation.

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