Prediction of turbulent forced convection of a nanofluid in a tube with uniform heat flux using a two phase approach

The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides work on the parameters of a 3--4 and 0.5 TeV center-of-mass (COM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (COM) that could be a factory for the $s$-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-$Z$ target and proceeding through the phase rotation and decay ($\ensuremath{\pi}\ensuremath{\rightarrow}\ensuremath{\mu}{\ensuremath{\nu}}_{\ensuremath{\mu}}$) channel, muon cooling, acceleration, storage in a collider ring, and the collider detector. We also present theoretical and experimental R plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the research and development since the feasibility study of muon colliders presented at the Snowmass '96 Workshop [R. B. Palmer, A. Sessler, and A. Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics (Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].

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Status of muon collider research and development and future plans

This review is devoted to the physics of current-carrying superconductors and normal metals having two or more stable states sustained by Joule self-heating. The creation, propagation, and localization of electrothermal domains and switching waves leading to the transition from one stable state to another in uniform and nonuniform samples are treated in detail. The connection between thermal bistability and hysteresis, dropping and stepped current-voltage characteristics, self-induced oscillations of current and voltage, selfreplication of electrothermal domains, and the formation of periodic and stochastic resistive structures are considered.

Self-heating in normal metals and superconductors

The term quantum turbulence denotes the turbulent motion of quantum fluids, systems such as superfluid helium and atomic Bose–Einstein condensates, which are characterized by quantized vorticity, superfluidity, and, at finite temperatures, two-fluid behavior. This article introduces their basic properties, describes types and regimes of turbulence that have been observed, and highlights similarities and differences between quantum turbulence and classical turbulence in ordinary fluids. Our aim is also to link together the articles of this special issue and to provide a perspective of the future development of a subject that contains aspects of fluid mechanics, atomic physics, condensed matter, and low-temperature physics.

https://www.pnas.org/content/pnas/111/Supplement_1/4647.full.pdf

Introduction to quantum turbulence

The recent development of nanotechnology led to the concept of using suspended nanoparticles in heat transfer fluids to improve the heat transfer coefficient of the base fluids. Specifically, numerical studies are reviewed in this study to get a clear view and detailed summary of the influence of several parameters such as type of nanoparticle and host liquid, particle volume concentration, particle size, particle shape, Brownian diffusion and thermophoresis effect on hydrodynamic and thermal characteristics of convective heat transfer using nanofluids. In addition, the paper provides detailed information about the most of commonly-used correlations which are utilized to predict the effective thermophysical properties of nanofluids. Finally, the main aim upon which the present work is based is to give a comprehensive review on different CFD approaches employed in numerical simulation of nanofluid flow, address the pros and cons of each approach, and find the suitable technique which gives more credible results as compared to experimental results.

Numerical study of convective heat transfer of nanofluids: A review

We describe a technique, using thin lines of triplet-state $\mathrm{He}_{2}^{*}$ molecular tracers created by femtosecond-laser field ionization of helium atoms, for visualizing the flow of the normal fluid in superfluid $^{4}\mathrm{He}$, together with its application to thermal counterflow in a channel. We show that, at relatively small velocities, where the superfluid is already turbulent, the flow of the normal fluid remains laminar, but with a distorted velocity profile, while at a higher velocity there is a transition to turbulence. The form of the structure function in this turbulent state differs significantly from that found in types of conventional turbulence. This visualization technique also promises to be applicable to other fluid dynamical problems involving cryogenic helium.

Visualization of the normal-fluid turbulence in counterflowing superfluid He 4

Turbulent flow pressure drop in various He II transfer system components

Transient heat transport in He II

The motion of micro-spheres in He II thermal counterflow has been measured using the Particle Image Velocimetry (PIV) technique. Although the tracer particles are able to track the motion of the normal fluid component, a significant discrepancy between the measured particle velocity and theoretical normal fluid velocity is observed. Further analysis of this velocity discrepancy suggests that it may be caused by the interaction between particles and vortex lines in the superfluid component. A semi-empirical correlation for the interaction force is developed and compared to the experimental results, from which new dynamic behavior of particles in He II is presented in the form of an effective kinematic viscosity of the superfluid.

The motion of micron-sized particles in He II counterflow as observed by the PIV technique

The new National High Magnetic Field Laboratory (NHMFL) at Tallahassee, Florida is committed to putting into operation in 1995 a 45-T Hybrid Magnet System to support research in steady, high magnetic fields. This facility will be accessible by qualified users world-wide on the basis of proposal and review. The more prominent components of this system will be a 24-MW resistive insert and a 120-MJ superconducting outsert. But successful achievement of the performance goals for the 45-T Hybrid System will depend on a number of unique, state-of-the-art subsystems and components. This paper describes the requirements and specifications on the individual subsystems and components in the context of the overall performance gears and reviews the plan for putting the whole together. >

S.W. Van Sciver

Papers

Visualization of the normal-fluid turbulence in counterflowing superfluid He 4

Turbulent flow pressure drop in various He II transfer system components

Transient heat transport in He II

The motion of micron-sized particles in He II counterflow as observed by the PIV technique

An overview of the 45-T hybrid magnet system for the new National High Magnetic Field Laboratory