A numerical investigation of the influence of land-sea breeze on the atmospheric effluents released at a coastal site

ABSTRACT. Mesoscale features of a coastal atmospheric boundary layer such as the land-sea circulation and the thermal internal boundary layer (TIBL) structure have been simulated using a two-dimensional numerical boundary layer model. Using Boussinesq approximation for horizontal momentum equations and hydrostatic approximation for vertical momentum equation the model solves the 'shallow water' equations year over a grid domain 80 km length on either side of the coastline and 2 km height. The influence of the land-sea breezes on the dispersion of pollutants released from a continuous point source located at the roast has been studied. The fumigation of pollutants from an offshore source into TIBL over the land has also been illustrated. The limitations associated with the model are also discussed.

Solute Transport Control at Channel Junctions Using Adjoint Sensitivity

Water quality control and the control of contaminant spill in water in particular are becoming a primary need today. Gradient descent sensitivity methods based on the adjoint formulation have proved to be encouraging techniques in this context for river and channel flows. Taking into account that most channels and rivers include junctions with other branches, the objective of this study is to explore the adjoint technique on a channel network to reconstruct the upstream boundary condition of the convection-reaction equation. For this purpose, the one-dimensional shallow water equations and the transport equation for a reactive solute are considered. The control is formulated through the gradient-descent technique supplied with a first-order iterative process. Both the physical and the adjoint equations are supplied with suitable internal boundary conditions at the junction and are numerically solved using a finite volume upwind scheme. The results reveal that the adjoint technique is capable of reconstructing the inlet solute concentration boundary condition in an acceptable number of iterations for both steady state and transient configurations using a downstream measurement location. It was also observed that the reconstruction of the boundary condition tends to be less effective the further away the measurement station is from the target.

Penyusunan Panduan Mandiri Pengembangan Kompetensi Agen Perubahan Internal

The main challenge for internal change agents is to overcome the ambiguity of their role as members of the organization who at the same time have to manage change in the organization. These challenges lead to the emergence of various boundaries encountered in organizations, which need to be spanned with the right strategy for change to be managed effectively. Unfortunately, there have not been many guidelines and training specifically provided to internal change agents, particularly regarding the constraints encountered and strategies for overcoming those boundaries. Generally, available training programs and guidance provided develop the ability to manage change in general. This self-guided manual for internal change agents aims to develop the ability of internal change agents, especially in overcoming the ambiguity of their role in the organization, by recognizing the boundaries they face and strategies for breaking those boundaries. This guide was developed based on the results of previous research that qualitatively explored the role of internal change agents in managing change in organizations, particularly in recognizing the boundaries encountered and their strategies for breaking boundaries so that organizational change can take place effectively. There are 3 stages carried out, namely 1) preparation, 2) guide development, and 3) evaluation and dissemination. This guidebook with the title “Spanning Boundaries, Becoming a Reliable Internal Change Agent” is organized into 4 parts, namely: Section (1) Organizational Change and the Role of Change Agents, (2) Boundaries Found in Implementing Change, (3) Strategies to Overcome Boundaries, (4) Personal Characters Needed to Overcome Boundaries and How to Develop It. It is hoped that because it is based on empirical data, the guidelines that have been compiled can develop the insight of internal change agents to be able to answer the concrete challenges faced to be able to manage change effectively. Keywords: Self-Guided Manual, Internal Change Agent, Boundary Spanning, Change Management Abstrak Tantangan utama agen perubahan internal adalah mengatasi ambiguitas perannya sebagai anggota organisasi yang pada saat yang bersamaan harus mengelola perubahan di organisasi. Tantangan ini menyebabkan munculnya berbagai batasan yang ditemui dalam organisasi, yang perlu dapat diretas dengan strategi yang tepat agar perubahan dapat dikelola secara efektif. Sayangnya belum banyak ditemukan panduan dan pelatihan yang khusus diberikan kepada agen perubahan internal, khususnya terkait dengan batasan yang ditemui dan strategi untuk meretas batasan tersebut. Umumnya program pelatihan dan panduan yang diberikan mengembangkan kemampuan mengelola perubahan secara umum. Panduan mandiri (self guided manual) untuk agen perubahan internal ini bertujuan untuk mengembangkan kemampuan agen perubahan internal, khususnya dalam mengatasi ambiguitas perannya dalam organisasi, dengan mengenali batasan yang dihadapi serta strategi meretas batasan tersebut. Panduan ini dikembangkan berdasar hasil penelitian yang dilakukan sebelumnya yang mengeksplorasi secara kualitatif peran agen perubahan internal dalam mengelola perubahan dalam organisasi, khususnya dalam mengenali batasan yang ditemui serta strategi mereka dalam meretas batasan agar perubahan organisasi dapat berlangsung secara efektif. Terdapat 3 tahapan yang dijalankan, yakni tahapan 1) persiapan, 2) pengembangan panduan, dan 3) evaluasi dan diseminasi. Panduan dengan judul “Meretas Batasan, Menjadi Agen Perubahan Internal yang Handal” disusun menjadi 4 bagian, yakni: Bagian (1) Perubahan Organisasi dan Peran Agen Perubahan, (2) Boundary yang Ditemui dalam Mengimplementasi Perubahan, (3) Strategi Mengatasi Boundary, (4) Karakter Personal yang Dibutuhkan untuk Mengatasi Boundary dan Cara Mengembangkannya. Diharapkan karena didasarkan pada data empiris, maka panduan yang disusun dapat mengembangkan wawasan agen perubahan internal untuk dapat menjawab tantangan konkrit yang dihadapi agar mampu mengelola perubahan secara efektif. Kata kunci: Panduan Mandiri, Agen Perubahan Internal, Boundary Spanning, Change Management

Effects of Selection of Inlet Perturbations, Multiphase and Turbulence Equations on Slug Flow Characteristics Using Altair® AcuSolve™

Selection of inlet perturbations, multiphase equations, and the turbulence equation may affect the development of slug flow using computational fluid dynamic simulation tools. The inlet perturbation, such as sinusoidal and random perturbations, play an essential role in inducing slug formation. Multiphase equations such as volume of fluid and level set methods are used to track and capture the gas-liquid immiscible interface. Similarly, turbulence equations such as Spalart Allmaras (SA), Detached Eddy Simulations (DES), k-omega, and k-epsilon can be used to predict the evolution of turbulence within the flow. At present, no direct comparison is available in the literature on the selection of (i) types of inlet perturbations, (ii) the choice of multiphase equations, and (iii) the turbulence equation on the development of slug flow using the Altair computational package. This article aims to compare the effects of the selection of inlet perturbations, multiphase models and turbulence equations on slug flow characteristics using Altair® AcuSolve™. The findings by Altair® simulation were compared to published experimental data and simulation works using ANSYS and STAR-CCM+. The slug flow characteristics of interest include slug morphology, a body length-to-diameter ratio, velocity, frequency, and pressure gradient. It was found that the slug flow could be developed for all combinations of settings. Although level set approach in Altair® can track fluid motion successfully, it has a limitation in modelling the convective transport of the multiphase mixture well, unlike ANSYS and STAR-CCM+. Compared to the standard level set method, the coupling of back-and-forth error compensation and correction with the level set function helps to capture the internal boundary more accurately by reducing errors caused by numerical diffusion in the transport of the level set. It was revealed that the Spalart Allmaras turbulence equation could mimic published experimental result better than DES as it produced the closest slug translational velocity. Since the frequency of the slugs for the developed models showed a good agreement with the published data, the models could be sufficient for the investigation of fluid-structure interaction.

Internal boundary value problems with displacement for the mixed-wave equation

В работе исследованы краевые задачи с внутреннекраевым смещением для модельного смешанно-волнового уравнения, которые являются обобщениями задачи Гурса и задач с данными на противоположных характеристиках. Показано, что при определенных условиях на заданные функции решение исследуемых задач существует, единственно и выписывается в явном виде. The paper investigates boundary value problems with an internal boundary displacement for a model mixed-wave equation, which are generalizations of the Goursat problem and problems with data on opposite characteristics. It is shown that, under certain conditions for given functions, the solution to the problems under study exists, is unique, and is written out in an explicit form.

Large eddy simulation of boundary-layer turbulence over the heterogeneous surface in the source region of the Yellow River

Lake breezes are proved by downdrafts and the divergence flows of zonal wind in the source region of the Yellow River (SRYR) in the daytime based on ERA-Interim reanalysis data. In order to depict the effect of the circulations induced by surface anomaly heating (patches) on the boundary-layer turbulence, the UK Met Office Large Eddy Model was used to produce a set of 1D strip-like surface heat flux distributions based on observations, which were obtained by a field campaign in the Ngoring Lake basin in the summer of 2012. The simulations show that for the cases without background wind, patch-induced circulations (SCs) promote the growth of convective boundary layer (CBL), enhance the turbulent kinetic energy (TKE), and then modify the spatial distribution of TKE. Based on phase-averaged analysis, which separates the attribution from the SCs and the background turbulence, the SCs contribute no more than 10 % to the vertical turbulent intensity, but their contributions to the heat flux can be up to 80 %. The thermal internal boundary layer (TIBL) reduces the wind speed and forms the stable stratification, which produces the obvious change of turbulent momentum flux and heat flux over the heterogeneous surfaces. The increased downdrafts, which mainly occur over the lake patches, carry more warm, dry air down from the free atmosphere. The background wind inhibits the SCs and the development of the CBL; it also weakens the patch-induced turbulent intensity, heat flux, and convective intensity.

Internal boundary and religious conflicts: the problems of national integration in post-colonial Nigeria

We investigated Nigerian’s post-colonial resurgences of internal boundary and religious conflicts that have bedeviled the country since independence based on the problems of national integration in post-colonial Nigeria. It argued that resurgences of internal boundary and religious conflicts in the country since liberation in 1960 are crops of expansionism in the sense that colonialism, while the post-colonial state could not avert the ills of colonial rule but rather re-invented the foreign strategy of division and law. It also argues that the scuffles for control of the naturally found resources in the localities are a result of “oppression, marginalization and government influence, uneven distribution of wealth and resources, nepotism and socio-religious bigotry,” which have over the years led religious groups, communities, local governments and States to a long-drawn-out deadly boundary and religious conflicts. The objective of this research is not only aim at highlighting the impact of internal boundary and religious conflicts on the Nigerian federation but also to draw the attention of Nigerian policymakers and researchers to the “neglect” of these issues, which have pitted groups between and even within states in the country, with deadly consequences, thereby questioning the principle of national integration and its essence in Nigeria. The methodology used in this research is the secondary source that has to do with published and unpublished works on the internal boundary, religious conflicts, and national integration. The paper submits that the existence of different natural resources found within the country should not always lead to the internal boundary and religious conflicts but cooperation amongst the people.