Implementation and performance analysis of efficient grid-free integral wall models in unstructured-grid LES solvers

Two zonal wall models based on integral form of the boundary layer differential equations, albeit with algebraic complexity, have been implemented in an unstructured-grid cell-centered finite-volume LES solver. The first model is a novel implementation of the ODE equilibrium wall model, where the velocity profile is expressed in the integral form using the constant shear-stress layer assumption and the integral is evaluated using a spectral quadrature method, resulting in a local and algebraic (grid-free) formulation. The second model, which closely follows the integral wall model of Yang et al. (Phys. Fluids 27, 025112 (2015)), is based on the vertically-integrated thin-boundary-layer PDE along with a prescribed composite velocity profile in the wall-modeled region. Several numerical challenges unique to the implementation of these integral models in unstructured mesh environments, such as the exchange of wall quantities between wall faces and LES cells, and the computation of surface gradients, are identified and possible remedies are proposed. The performance of the wall models is assessed both in a priori and a posteriori settings against the traditional finite-volume based ODE equilibrium wall model, showing a comparable computational cost for the integral wall model, and superior performance for the spectral implementation over the finite-volume based approach. Load imbalance among the processors in parallel simulations seems to severely degrade the parallel efficiency of finite-volume based ODE wall model, whereas the spectral implementation is remarkably agnostic to these effects

Wind tunnel study of wind farms with alternating 2- and 3-bladed wind turbines

With offshore wind farms gaining substantial momentum in recent years, 2-bladed turbines (2BT) are increasingly becoming a viable alternative to 3-bladed counterparts (3BT). In this wind tunnel study, model wind farms with alternating rows of 3BT and 2BT were explored for potential benefits associated with enhanced momentum available within the arrays and reduced costs due to the reduction of blades. Two arrays of aligned turbines with streamwise separation of five and ten rotor diameter d (Sx = Δx/d =5 and 10) were operated in a turbulent boundary layer flow. They shared the same transverse turbine spacing of Sy = Δy/d =2.5. High-resolution velocity measurements were made with hotwire anemometry at various locations in the wake and the power output of turbines was measured simultaneously. Comparison of the flow between an array with only 3BT and that with alternating 2BT and 3BT shows enhanced mean velocity and reduced turbulence levels for the latter in Sx = 5 case. The pre-multiplied spectra of the flow at selected locations within the wind farm suggest that large energetic structures at top-tip and hub height are dampened by 2BT, with the potential to reduce turbulent loading on downwind turbines. Although the reduced mixing at top tip height behind 2BT causes the momentum recovery rate to diminish, the available momentum at downstream turbine is still higher than corresponding 3BT in the Sx = 5 case. Overall performance gain from marginally enhanced power statistics of 3BT operating in the wake of 2BT is offset by the diminished performance of 2BT inside the farm, resulting in comparable performance between the two configurations

The Rise of Islamophobia and Religious Intolerance: A Menace to Pluralism and Global Peace

The rise of Islamophobia, religious intolerance, and racism has been a major threat to global peace and plurality. The study aims to analyse the Islamophobia literature that misinterprets religious teachings and fuels hatred and violence towards Muslim communities around the world. This is an alarming trend that must be addressed to build a more peaceful and tolerant society as the consequences of Islamophobia are damaging to global peace. Islamophobia indicates that religious intolerance is increasingly accompanied by hatred, fear, and antagonism around the globe. This essay examines the trends, underlying reasons for, and consequences of religious intolerance and Islamophobia on global harmony and peaceful coexistence. Religious intolerance permeates physical and verbal assaults forging discrimination and marginalization of Muslim communities and leading to the erosion of civil liberties as well as the rise of xenophobia and social disintegration. It fuels prejudice, animosity and terrorism against Muslims, and fosters an upsurge in human rights violations, civil liberties, political turmoil and global unrest. The study presents workable measures to slow the spread of religious intolerance and Islamophobia. &nbsp

The Moderating Effect of Time Pressure on Packaging Elements and Consumer Buying Behavior: A case of Nestle Pakistan

The purpose of this study to measure whether three product packaging Elements Wrapper Design, Packaging Material and Printed Information Influences Consumer Buying Behavior or does Time Pressure shows a moderating relationship. This study determines the importance of these elements when they purchase Nestle products during short time period. In this research highlighted that companies cannot afford to ignore the importance of time constraints and packaging elements of the products on consumer Buying Behavior. The study was conduct in District Vehari, Punjab Pakistan. Data was collecting to the students of Higher Educational Institution in District Vehari. Structured Questionnaire was used that consist on five point Likert Scale. Multiple Regression Analysis, ANOVA, coefficient was used to test the variables

Simultaneous measurement of quality factor and wavelength shift by phase shift microcavity ring down spectroscopy

Optical resonant microcavities with ultra high quality factors are widely used for biosensing. Until now, the primary method of detection has been based upon tracking the resonant wavelength shift as a function of biodetection events. One of the sources of noise in all resonant-wavelength shift measurements is the noise due to intensity fluctuations of the laser source. An alternative approach is to track the change in the quality factor of the optical cavity by using phase shift cavity ring down spectroscopy, a technique which is insensitive to the intensity fluctuations of the laser source. Here, using biotinylated microtoroid resonant cavities, we show simultaneous measurement of the quality factor and the wavelength shift by using phase shift cavity ring down spectroscopy. These measurements were performed for disassociation phase of biotin-streptavidin reaction. We found that the disassociation curves are in good agreement with the previously published results. Hence, we demonstrate not only the application of phase shift cavity ring down spectroscopy to microcavities in the liquid phase but also simultaneous measurement of the quality factor and the wavelength shift for the microcavity biosensors in the application of kinetics measurements

Mathematical Modeling and Review of Pine Wilt Disease

Pine Wilt Disease (PWD), caused by the pinewood nematode (PWN) Bursaphelenchus xylophilus, causes significant losses in coniferous forests in eastern Asia, including Japan, China, and South Korea, as well as western Europe, including Portugal. The results of the research papers given at the International Symposium on Pine Wilt Disease (IUFRO Working Party Meeting 4.04.03) in Nanjing, China, in July 2009 are summarized in this article. The basic themes discussed included pine wilt disease (PWD), the pinewood nematode (PWN) Bursaphelenchus xylophilus, and other PWN-associated microorganisms that play a significant role in PWD, such as bacteria (e.g., Pseudomonas fluorescens). The majority of the papers are based on PWD-PWN research in East Asia and Russia. The following are some of the specific topics covered: 1) fundamental concepts of PWD development, 2) pathogenicity, 3) host-parasite relationships, including histopathology of diseased conifers and the role of toxins from bacteria-nematode ecto-symbionts, 4) PWN life cycle and transmission, 5) B. xylophilus dissemination models, 6) associations (with other nematodes), 7) diagnostics, 8) quarantine and control of the PWN and 9) biocontrol of the PWN