scholarly journals The instability of a sedimenting suspension of weakly flexible fibres

2014 ◽  
Vol 756 ◽  
pp. 935-964 ◽  
Author(s):  
Harishankar Manikantan ◽  
Lei Li ◽  
Saverio E. Spagnolie ◽  
David Saintillan
Keyword(s):  
Mean Field Theory ◽  
Mean Field ◽  
Suspension Stability ◽  
Dominant Effect ◽  
Flexible Bodies ◽  
Fibre Concentration ◽  
Orientation Fields ◽  
The Stability ◽  
Rotational Brownian Motion

AbstractSuspensions of sedimenting slender fibres in a viscous fluid are known to be unstable to fluctuations of concentration. In this paper we develop a theory for the role of fibre flexibility in sedimenting suspensions in the asymptotic regime of weakly flexible bodies (large elasto-gravitation number). Unlike the behaviour of straight fibres, individual flexible filaments rotate as they sediment, leading to an anisotropic base state of fibre orientations in an otherwise homogeneous suspension. A mean-field theory is derived to describe the evolution of fibre concentration and orientation fields, and we explore the stability of the base state to perturbations of fibre concentration. We show that fibre flexibility affects suspension stability in two distinct and competing ways: the anisotropy of the base state renders the suspension more unstable to perturbations, while individual particle self-rotation acts to prevent clustering and stabilizes the suspension. In the presence of thermal noise, the dominant effect depends critically upon the relative scales of flexible fibre self-rotation compared to rotational Brownian motion.

scholarly journals Impact of the Nuclear Equation of State on the Stability of Hybrid Neutron Stars

Universe ◽  
2019 ◽  
Vol 5 (8) ◽  
pp. 186 ◽  
Author(s):  
Mateusz Cierniak ◽  
Tobias Fischer ◽  
Niels-Uwe Bastian ◽  
Thomas Klähn ◽  
Marc Salinas
Keyword(s):  
Equations Of State ◽  
Mean Field Theory ◽  
Mean Field ◽  
Type Model ◽  
Two Phase ◽  
Relativistic Mean Field ◽  
Nuclear Equation Of State ◽  
Hot Matter ◽  
The Stability ◽  
Quark Phase

We construct a set of equations of state (EoS) of dense and hot matter with a 1st order phase transition from a hadronic system to a deconfined quark matter state. In this two-phase approach, hadrons are described using the relativistic mean field theory with different parametrisations and the deconfined quark phase is modeled using vBag, a bag–type model extended to include vector interactions as well as a simultaneous onset of chiral symmetry restoration and deconfinement. This feature results in a non–trivial connection between the hadron and quark EoS, modifying the quark phase beyond its onset density. We find that this unique property has an impact on the predicted hybrid (quark core) neutron star mass–radius relations.

scholarly journals Effect of weak disorder on the BCS–BEC crossover in a two-dimensional Fermi gas

2017 ◽  
Vol 31 (09) ◽  
pp. 1750066
Author(s):  
Ayan Khan ◽  
B. Tanatar
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Fermi Gas ◽  
Ultracold Fermi Gas ◽  
Condensate Fraction ◽  
Two Dimensional ◽  
Weak Disorder ◽  
Unique Nature

In this paper, we study the two-dimensional (2D) ultracold Fermi gas with weak impurity in the framework of mean-field theory where the impurity is introduced through Gaussian fluctuations. We have investigated the role of the impurity by studying the experimentally accessible quantities such as condensate fraction and equation of state of the ultracold systems. Our analysis reveals that at the crossover, the disorder enhances superfluidity, which we attribute to the unique nature of the unitary region and to the dimensional effect.

Role of molecular bend angle and biaxiality in the stabilization of the twist-bend nematic phase

Soft Matter ◽  
2020 ◽  
Vol 16 (18) ◽  
pp. 4350-4357 ◽  
Author(s):  
Wojciech Tomczyk ◽  
Lech Longa
Keyword(s):  
Field Theory ◽  
Nematic Phase ◽  
Mean Field Theory ◽  
Mean Field ◽  
Structural Features ◽  
Bend Angle ◽  
Nematic Phases

Within mean-field theory for V-shaped molecules, we have investigated how the alteration of a molecule's structural features influence the stabilization of modulated and non-modulated nematic phases.

THE ROLE OF THE NUCLEAR MATTER COMPRESSION MODULUS IN NEUTRON STARS

2004 ◽  
Vol 13 (07) ◽  
pp. 1519-1524 ◽  
Author(s):  
VERÔNICA A. DEXHEIMER ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
MOISÉS RAZEIRA ◽  
MANFRED DILLIG
Keyword(s):  
Neutron Stars ◽  
Nuclear Matter ◽  
Body Problem ◽  
Mean Field Theory ◽  
Mean Field ◽  
Compression Modulus ◽  
Baryon Number ◽  
Many Body ◽  
Relativistic Mean Field

For the nuclear many body problem at high densities, formulated in the framework of a relativistic mean-field theory, we investigate in detail the compression modulus of nuclear matter as a function of the effective nucleon mass. We include consistently in our modelling chemical equilibrium as well as baryon number and electric charge conservation and investigate properties of neutron stars. Among other predictions we focus on the dependence of the maximum mass of a sequence of neutron stars as a function of the compression modulus and the nucleon effective mass.

A RENORMALIZATION GROUP APPROACH FOR MANY-FERMION PROBLEMS

1992 ◽  
Vol 06 (05n06) ◽  
pp. 749-758 ◽  
Author(s):  
R. SHANKAR
Keyword(s):  
Renormalization Group ◽  
Landau Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Free Fermion ◽  
Fermion System ◽  
Group Approach ◽  
Fermionic Systems ◽  
Renormalization Group Approach ◽  
The Stability

A renormalization group transformation (RGT) that permits us to analyze the stability of fermionic systems to various perturbations in any number of dimensions is developed. An RGT that leaves invariant the free fermion system (on or off a lattiice) is defined and interactions are classified as relevent, irrelevent or marginal. It is shown how the RGT automatically considers competing instabilities simultaneously, in contrast to mean field theory, which focuses on just one. It is shown that at weak coupling only the BCS coupling is relevent unless there is nesting. Both Landau theory and the Kohn-Luttinger argument are discussed in this context.

GROUND STATE PROPERTIES OF SUPERHEAVY NUCLEI IN RELATIVISTIC MEAN FIELD THEORY

2006 ◽  
Vol 15 (07) ◽  
pp. 1613-1624
Author(s):  
H. F. ZHANG ◽  
J. Q. LI ◽  
W. ZUO ◽  
X. H. ZHOU ◽  
Z. G. GAN ◽  
...  
Keyword(s):  
Mean Field Theory ◽  
Mean Field ◽  
Decay Chain ◽  
Stable Region ◽  
Bcs Theory ◽  
Heavy Nuclei ◽  
Relativistic Mean Field ◽  
The Stability ◽  
Super Heavy Nuclei ◽  
The Continuum

In the framework of the relativistic mean field (RMF) theory, the stability and ground properties of super-heavy nuclei are discussed. Our study indicated that the current synthesized super-heavy nuclei (SHN) actually appear in the stable region, and adding more neutrons will not increase their stability. The study of nuclei from 287115 α decay chain showed that they are usually deformed, the magnitudes of their shell gaps are much smaller than those of nuclei before the actinium region, so that the shell effect is weakened, and SHN are usually not stable. A common phenomenon is that the Fermi surface of the proton is close to the continuum, the resonant continuums exist in SHN, because the SHN are usually neutron deficient. Although bulk properties can be described by the RMF+BCS theory, further study is needed. Density dependent delta pairing interaction can improve the treatment of the pairing and thus improve the level distribution in the continuum.

EFFECTS OF TEMPERATURE ON THE STABILITY OF PROTONEUTRON STARS WITH HYPERONS

2012 ◽  
Vol 27 (02) ◽  
pp. 1250008 ◽  
Author(s):  
ZI YU ◽  
WENBO DING ◽  
NINGNING LIU ◽  
QING LUO
Keyword(s):  
Mean Field Theory ◽  
Mean Field ◽  
Mass Range ◽  
Relativistic Mean Field ◽  
Sn 1987A ◽  
Higher Temperature ◽  
Effects Of Temperature ◽  
The Stability ◽  
Protoneutron Stars ◽  
Protoneutron Star

In the framework of the relativistic mean field theory, the stability of thermal protoneutron stars is investigated. There is a highest possible temperature for a stable protoneutron star. A stable protoneutron star may be a metastable one if its mass is too large. As the temperature increases, the metastable mass range of protoneutron stars narrows. With the increase of temperature, the probability that a stable protoneutron star is a metastable one increases. A really stable protoneutron star with higher temperature can contain more species of hyperons. The case of SN 1987A is analyzed connected with the results in this article.

scholarly journals Evolution of the Kondo lattice electronic structure above the transport coherence temperature

2020 ◽  
Vol 117 (38) ◽  
pp. 23467-23476
Author(s):  
Sooyoung Jang ◽  
J. D. Denlinger ◽  
J. W. Allen ◽  
V. S. Zapf ◽  
M. B. Maple ◽  
...  
Keyword(s):  
Electric Field ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spectral Weight ◽  
Kondo Lattice ◽  
Crystalline Electric Field ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Sufficient Detail ◽  
Arpes Data

The temperature-dependent evolution of the Kondo lattice is a long-standing topic of theoretical and experimental investigation and yet it lacks a truly microscopic description of the relation of the basic f-c hybridization processes to the fundamental temperature scales of Kondo screening and Fermi-liquid lattice coherence. Here, the temperature dependence of f-c hybridized band dispersions and Fermi-energy f spectral weight in the Kondo lattice system CeCoIn5is investigated using f-resonant angle-resolved photoemission spectroscopy (ARPES) with sufficient detail to allow direct comparison to first-principles dynamical mean-field theory (DMFT) calculations containing full realism of crystalline electric-field states. The ARPES results, for two orthogonal (001) and (100) cleaved surfaces and three different f-c hybridization configurations, with additional microscopic insight provided by DMFT, reveal f participation in the Fermi surface at temperatures much higher than the lattice coherence temperature,T*≈45K, commonly believed to be the onset for such behavior. The DMFT results show the role of crystalline electric-field (CEF) splittings in this behavior and a T-dependent CEF degeneracy crossover belowT*is specifically highlighted. A recent ARPES report of low T Luttinger theorem failure for CeCoIn5is shown to be unjustified by current ARPES data and is not found in the theory.

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