The effect of friction in the thermal convection instability of granular fluids is studied by means of molecular dynamics simulations. It is found that the transitions between different convective states (zero, one, and two rolls) are primarily governed by the average energy loss per collisions and not by the friction and restitution coefficients separately, and can be roughly described in terms of a single effective restitution coefficient. The average energy loss per collisions, for a fixed value of the restitution coefficient, shows a maximum for a friction coefficient kappa approximately 0.3. The presence of this maximum manifests itself as a reentrant behavior in the transition lines in parameter space when the value of the friction coefficient is increased beyond 0.3.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1103/PhysRevE.72.011305 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Characteristics of transition to turbulence in a healthy thoracic aorta using large eddy simulation.
Sci Rep
January 2025
University of Ulsan, 93 Daehak-ro, Nam-gu, Ulsan, 680-749, Republic of Korea.
This study employed large eddy simulation (LES) with the wall-adapting local eddy-viscosity (WALE) model to investigate transitional flow characteristics in an idealized model of a healthy thoracic aorta. The OpenFOAM solver pimpleFoam was used to simulate blood flow as an incompressible Newtonian fluid, with the aortic walls treated as rigid boundaries. Simulations were conducted for 30 cardiac cycles and ensemble averaging was employed to ensure statistically reliable results.
View Article and Find Full Text PDFImproving MRI turbulence quantification by addressing the measurement errors caused by the derivatives of the turbulent velocity field - Sequence development and in-vitro validation.
Magn Reson Imaging
January 2025
Institute of Fluid Mechanics, University of Rostock, Rostock, Germany.
Purpose: To improve the current method for MRI turbulence quantification which is the intravoxel phase dispersion (IVPD) method. Turbulence is commonly characterized by the Reynolds stress tensor (RST) which describes the velocity covariance matrix. A major source for systematic errors in MRI is the sequence's sensitivity to the variance of the derivatives of velocity, such as the acceleration variance, which can lead to a substantial measurement bias.
View Article and Find Full Text PDFThe synergies of air quality monitoring program: Information disclosure and pollution control.
J Environ Manage
January 2025
Chongqing Environmental Consulting Co., Ltd., CISDI Group Co., Ltd., Chongqing, China. Electronic address:
To deal with the increasingly severe climate crisis and environmental pollution, China launched a nationwide real-time air quality monitoring program in three batches, a milestone moment in its environmental governance history. Using the time-varying difference-in-differences model, this study explores the synergies of this program across 284 cities from 2009 to 2019. The findings are as follows: (1) With environmental information disclosed, the national air quality monitoring program can reduce the outdoor fine particulate matter concentration by an overall effect of 3.
View Article and Find Full Text PDFChanges in Bone Mineral Density After Parathyroidectomy in Patients With Primary Hyperparathyroidism.
J Surg Res
January 2025
Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama. Electronic address:
Introduction: Patients with primary hyperparathyroidism (PHPT) are prone to low bone mineral density (BMD). This study aimed to explore factors associated with improved bone health after parathyroidectomy (PTx).
Methods: We conducted a retrospective analysis of patients who underwent PTx for PHPT at our institution between 2016 and 2020.
Evaluation of lumbar vertebral bone quality using T1-weighted MRI: Can it differentiate normal, osteopenia, and osteoporosis?
J Clin Densitom
January 2025
University of Health Sciences, Umraniye Training and Research Hospital, Department of Radiology, Istanbul, Turkey.
Background: Osteoporosis, a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration, poses a significant public health challenge globally. While the gold standard for diagnosing osteoporosis is dual-energy X-ray absorptiometry (DXA), its use is limited by factors like spinal deformities and artifacts. This study aims to explore the potential of routine T1-weighted MRI sequences in predicting osteopenia and osteoporosis through the vertebral bone signal (VB) to cerebrospinal fluid signal (CSF) ratio.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!