bluuebunny/crossref_metadata_2025 huggingface dataset:
EXPERIENCE IN THE VICE PRINCIPALSHIP: PREPARATION FOR LEADING SCHOOLS?
Authors: GREENFIELD WILLIAM D. , MARSHALL CATHERINE , REED DONALD B.
Published: February 2008

This report examines the function of experience in the role of vice‐principal as preparation for the school principalship, proposing that a dysfunctional socialization outcome of this career entry pattern is the development of a role orientation that emphasizes managing rather than leading the school. The authors differentiate these two dimensions of the administrative role by suggesting that the managerial function emphasizes organizational stability and maintenance of the day‐to‐day operation, and that the leadership function emphasizes improvements in instructional and organizational arrangements facilitating teaching and learning. While a balance in functions is the preferred orientation implicit in theoretical as well as prescriptive models of the principalship, and principals themselves espouse the desirability of an instructional leadership emphasis, most empirical studies of the principalship indicate a substantial skewing of emphasis in the direction of managerial activities. The paper offers an empirically grounded theoretical explanation of this occurrence. Based on data from the studies of the enculturation process and the work activities of vice‐principals, and guided by socialization theory, the report discusses role‐learning implications of experience in the vice‐principalship role and concludes with seven propositions for further study.
PRIMITIVE SEMANTIC NOTIONS ABOUT HIERARCHICAL STRUCTURES: IMPLICATIONS FOR EDUCATIONAL ORGANISATIONS AND EDUCATIONAL KNOWLEDGE
Authors: CORSON DAVID
Published: February 2008

This article proposes that both the new critique of organisation theory in education and the “new” sociology of education overlook, in their respective knowledge claims, a fundamental disposition in the human species to view the phenomenal and the metaphysical worlds in a hierarchically structured way. We perceive organisational and epistemological structures much more consistently than some theorists would allow. This consistency is due to the effects of two types of semantic primitives which operate to constrain our world views and whose influence we bypass only with difficulty and only by dint of rigorous intellectual effort. After reviewing some of the various epistemological claims that are made both about educational organisations and about the knowledge that concerns educational organisations, the article discusses the two types of semantic primitives that seem to impinge upon our world views: universal semantic primitives; and acquired semantic primitives. Implications for human perspectives on the world and for theory in educational administration are drawn from the discussion. Methods for escaping the constraints of these two types of primitives are proposed.
THE APPLICATION OF ORGANIZATIONAL MODELS TO THE STUDY OF SCHOOLS
Authors: STURMAN A.
Published: February 2008

The application of different models of organization to the study of schools is common in the literature on organizational theory. This literature distinguishes rational models, such as the bureaucratic ideal type, from natural systems models, such as the concept of schools as loose‐coupled systems and the image of schools as political arenas. This article examines the extent to which some specially selected schools in Australia and New Zealand can be viewed as resembling certain organizational models. The article concludes that there is no one model which is suitable for describing schools although many of the different models described by theorists seem to be relevant to the schools studied. The article also seeks to isolate some of the factors that result in schools resembling certain organizational models rather than others.
THE SUPERINTENDENT AS INSTRUCTIONAL LEADER: FINDINGS FROM EFFECTIVE SCHOOL DISTRICTS
Authors: MURPHY JOSEPH , HALLINGER PHILIP
Published: February 2008

The study reported on in this article examines how instructional leadership is exercised by superintendents in effective school districts. We employ concepts drawn from school effectiveness studies and from organizational literature on coordination and control in an attempt to understand how superintendents organize and manage instruction and curriculum in these effective districts. Specific instructional management practices are examined within a framework of six major functions, setting goals and establishing expectations and standards, selecting staff, supervising and evaluating staff, establishing an instructional and curricular focus, ensuring consistency in technical core operations, and monitoring curriculum and instruction. Based on interviews with superintendents from 12 of the most instructionally effective school districts in California and analysis of selected district documents, we present descriptions of district‐level policies and practices that these superintendents use to coordinate and control the instructional management activities of their principals. Similarities and differences in the patterns of control and coordination found in these districts are highlighted. The implications of the findings are then examined in light of recent findings regarding coupling and linkages in schools. The results of this study suggest that superintendents in instructionally effective school districts are more active “instructional managers” than previous descriptions of superintendents would have led us to expect. In particular, coordination and control of the technical core appears more systematic in these districts. The results do not, however, provide a uniform picture of how instruction is coordinated and controlled. A wide range of both culture building activities and bureaucratic policies and practices were emphasized by the superintendents in this study as they exercised their instructional leadership roles.
SCHOOL ADMINISTRATORS AND ORGANIZATIONAL STRESS: MATCHING THEORY, HUNCHES AND DATA
Authors: FEITLER FRED C. , TOKAR EDWARD B.
Published: February 2008

This study presents data and discusses the relationship between occupational stress and organization theory for school administrators. Classical organization theory, focusing upon organizations as primarily bureaucratic in nature, and person‐environment P‐E fit theory, viewing the employee within the context of a work environment, are two broad theoretical frameworks that serve as bases for analysis and discussion. The objectives of the study follow: to report descriptive data about perceived levels of occupational stress, sources of stress, symptoms and coping strategies for building administrators from differing school settings; to provide comparisons between dependent variables of stress for specific independent variables such as school level and type; to apply organization theory to explain differences and relationships among variables; and to present a conceptually sound basis for further research on stress in education. A factorial ANOVA was used to test for main effect differences for the group dependent means for perceived occupational stress and the independent variables of level of school and school type. Several discriminant analyses were performed to determine the nature of discriminant functions for the dependent variables. Theoretically, highly bureaucratic schools should exhibit less stress than less bureaucratic schools. This was not supported. Person‐environment fit theory was better able to predict levels of perceived stress for school administrators.
SCHOOL ENVIRONMENTAL CHARACTERISTICS AND CONSTRAINTS: A CROSS‐CULTURAL PERSPECTIVE ON CANADIAN AND SWAZILAND SCHOOLS
Authors: JACK LAM Y.L.
Published: February 2008

Using a recently developed instrument, the environmental characteristics and constraints of Canadian public schools and those of Swaziland were captured in respective profiles for detailed comparison. Problems unique to the school in each cultural setting were identified and the adaptation processes each system had undergone were explored.
THE JOURNAL OF EDUCATIONAL ADMINISTRATION: THE FIRST TWENTY‐FIVE YEARS
Authors: ROSS THOMAS A.
Published: February 2008

With this issue The Journal of Educational Administration commences its twenty‐fifth year of publication. Just five years ago, on the occasion of its twentieth year of publication, I reviewed the role of the J.E.A. in a special editorial — “Twenty Years A Journal: An Anniversary Statement.” Since that time there have been several developments in the publication of the J.E.A. that are perhaps worthy of comment on this our silver jubilee.
PRINCIPALLY SPEAKING: AN ANALYSIS OF THE INTERPERSONAL COMMUNICATIONS OF SCHOOL PRINCIPALS
Authors: BREDESON PAUL V.
Published: February 2008

Communication in any organization is a complex phenomenon. Public schools are people‐centered enterprises in which the primary tasks of teaching and learning are accomplished verbally. Within each school, the principal is uniquely positioned to regulate these communications activities. The research reported here sought to examine how five school principals managed communications in their schools. Three major questions guided the research. What are the preferred modes and levels of communications activities utilized by principals? What are the major messages communicated through various modes and at different levels by principals? What do the communications activities of individual principals tell us about how principals interpret their leadership role in school, how they set administrative priorities, and how they put their beliefs and values into practice? The findings indicate that the communications activities of school principals are dominated by dyadic interpersonal contacts. The major purpose of these dyadic interpersonal exchanges were maintenance messages which related to policies, procedures, and regulations for organizing, operating and perpetuating the school. As an adaptation to the nature of a principal's work life, each principal demonstrated a pragmatic preference for accomplishing his/her communications through talk even when written messages or other mechanisms for message delivery would have been more efficient. Finally, the principals believed that the success of their communications activities in school was characterized by openness, honesty, high visibility, and the ability and capacity to listen.
THE INFLUENCE OF SUPERINTENDENTS ON THE ACADEMIC ACHIEVEMENT OF SCHOOL DISTRICTS
Authors: WEAVER HART ANN , OGAWA RODNEY T.
Published: February 2008

It is often assumed that administrators exert an influence on the performance of their organizational units. While there is mounting evidence regarding the influence exerted by principals on the academic performance of schools, little attention has been paid to examining the influence exerted by superintendents on the academic performance of school districts. In this study, a sample of California school districts was employed to estimate the influence of superintendents, controlling for environmental and district factors, on the performance of sixth and twelfth grade students on the mathematics and reading sections of the standardized achievement test of the California Assessment Program. An analysis of the components of variation was conducted to determine the relative percent of variance attributable to environmental and district factors and to superintendents. It was found that superintendents exerted a small influence on the academic performance of school districts. Further, it was found that superintendents had a relatively greater influence on sixth grade test scores than they had on twelfth grade test scores.
ONE HUNDRED DISSERTATIONS: A REVIEW OF THE UNIVERSITY OF NEW ENGLAND MORALE RESEARCH PROJECT
Authors: SMITH KEVIN R.
Published: February 2008

Graduate students of the University of New England (U.N.E.) during the period 1970–1984 wrote one hundred dissertations on morale in a wide variety of educational institutions. The Staff Morale Questionnaire (S.M.Q.) developed and progressively refined at U.N.E. was extensively used in these and other studies in Australia. The project's greatest value lay in the way it enabled external (i.e. off‐campus) students to develop their academic critical abilities in a guided research effort, and in the ripple effect which has enabled numerous administrators in Australian schools to gain some sensitisation to and understanding of the importance of organisational morale.
THE ADMINISTRATIVE CONTROL OF PRINCIPALS IN EFFECTIVE SCHOOL DISTRICTS
Authors: MURPHY JOSEPH , HALLINGER PHILIP , PETERSON KENT D. , LOTTO LINDA S.
Published: February 2008

In this study the authors set out to investigate the nature of administrative control in school districts in general and the control processes and activities employed in instructionally effective school districts in particular. Nine control functions are identified which are assumed to affect student outcomes by influencing the culture and technology (curriculum and instruction) of schools. Data were collected from interviews of superintendents in 12 effective school districts in California. The findings revealed inter alia more district‐level control of principal behavior and site activity than anticipated; control functions that were pervasive and connected; a wide range of control mechanisms; and the key role of the superintendent in connecting schools and district offices.
PREDICTORS OF TEACHER BURNOUT
Authors: SARROS JAMES C. , SARROS ANNE M.
Published: February 2008

This paper describes the nature of burnout among teachers, examines the differences in burnout between teachers and school‐based administrators, and explores the extent to which specific work factors predict teacher burnout. Teachers were experiencing less Emotional Exhaustion and Depersonalization burnout, but more Personal Accomplishment burnout than other helping service professionals. Their levels of Emotional Exhaustion and Personal Accomplishment burnout were higher than those for administrators. Both job satisfaction and job challenge were significant predictors of each burnout sub‐scale. The findings indicate that burnout is both the result of organizational factors such as work load, as well as the result of failure of the job to satisfy the motivational needs of teachers to be challenged and rewarded by their work. These results dispute some established research findings, and contribute new evidence to the growing data base on educator burnout.
PRINCIPALS' LEADERSHIP STYLES AS CHANGE FACILITATORS IN CURRICULAR RELATED ACTIVITIES
Authors: AVI‐ITZHAK TAMARA E. , BEN‐PERETZ MIRIAM
Published: February 2008

The present study is concerned with assessing the factors which affect principals' roles as change facilitators in the area of curricular innovation. It is designed to identify the prevailing modes of principals' change facilitator leadership styles in curricular related activities and to estimate the relative predictive ability of policy, strategy (i.e. values), organizational and background factors in explaining the variance of these leadership styles. A random sample of 69 principals from the school district of one of the largest cities in Israel participated in the study. Three mutually exclusive modes of principals' change facilitator leadership styles — Responder, Manager and Initiator — emerged from the analysis. The totality of the factors in the research model explained 20, 31 and 48 percent of the variance respectively in the three styles. Results indicate that background and organizational factors contribute relatively more in explaining the variance in these modes than policy and strategy factors.
THE WAY EXAMINERS ASSESS CRITICAL THINKING IN EDUCATIONAL ADMINISTRATION THESES
Authors: SIMPKINS W.S.
Published: February 2008

Did a set of examiner's reports written on educational theses subscribe to a common view of critical thinking? An analysis indicated that an idealized style of critical thinking was embodied in examiners' comments, one which combined the imagery of detached rationality with the imagery of imaginative insight. This functional definition, applied for the purpose of assessment, appears to represent a mixture of assumptions taken from traditional and emergent research traditions in educational administration. It is conjectured that this functional definition may represent a negotiated meaning, arrived at in the light of conflicting intellectual and cultural pressures experienced in the academic study of educational administration.
DECENTRALIZATION, DEVOLUTION AND THE TEACHER: PARTICIPATION BY TEACHERS IN THE DECISION MAKING OF SCHOOLS
Authors: CHAPMAN JUDITH D.
Published: February 2008

The implementation of the policy of devolution in the government school system of Victoria, Australia, has significantly enhanced the opportunities for teachers to become involved in the decision making of schools. This article reports on a study designed to investigate the factors associated with involvement. Analysis of the data found teacher involvement in the decision making of schools to be associated with: gender; seniority and organizational responsibility; age and teaching experience; affiliation with the teachers association; the influence of the principal; the individual's sense of personal, political and professional efficacy; the individual's confidence and trust in the organization and its administration; the conflicting demands, anxiety and pressure of time; and the perceived effects of participation on curriculum and teaching practice.
ORGANIZATIONAL CLIMATE AND WORK SATISFACTION: THE CASE OF BEDUIN ELEMENTARY SCHOOLS IN ISRAEL
Authors: NEUMANN YORAM , REICHEL ARIE , ABU SAAD ISMAEL
Published: February 2008

The purpose of this study is to focus on Israeli Beduin school teachers and examine the nature of their satisfaction with the job, perception of organizational climate, and their interaction. The 185 elementary school teachers included in the study are predominantly Israeli Arabs, expected to function within a modern organization and become change agents to the Beduin pupils. Job satisfaction has been measured by twenty‐three items, resulting in two major factors: task issues and interaction with other people. Organizational climate includes fifty‐four items, condensed into two factors: principal‐teachers relations, and negative feelings about the school's atmosphere. The effect of climate on satisfaction was examined in two separate regression models, one where the dependent variable is the task aspect of satisfaction, and the other is the human relations aspect. Climate factors have been found to have a strong and meaningful explanatory power only in the former satisfaction model. The latter has an overall weak explanatory value. Throughout the analyses, the role of principal‐teachers relations appears to be dominant.
DECISION SUPPORT SYSTEMS IN ACADEMIC ADMINISTRATION
Authors: TURBAN EFRAIM , CAMERON FISHER JANET , ALTMAN STEVE
Published: February 2008

A decision support system (DSS) is a flexible, interactive, computerized approach intended to support administrators in their decision making activities and which is capable of providing direct, personal support for complex, managerial decisions. This paper presents an overview of DSS's major characteristics which can integrate the intellectual resources of individuals with the capabilities of the computer to improve the quality of decisions. Following a discussion of its capabilities, the various components of a DSS (database, model base, hardware and user‐system interface) are examined as well as the development tools needed. Examples of the applications of DSSs in two universities provide insight into the benefits a DSS can bring to educational administration. Finally, the paper considers various development and implementation issues pertaining to a decision support system in academic administration.
ADMINISTRATOR BURNOUT: FINDINGS AND FUTURE DIRECTIONS
Authors: SARROS JAMES C.
Published: February 2008

The increasing incidence of educator stress and burnout is cause for concern. Nonetheless, the findings of this Canadian‐based study indicate that school principals are experiencing less than average levels of Emotional Exhaustion and Depersonalization burnout, and an average level of Personal Accomplishment burnout. Work conditions most likely to contribute to burnout were work stress, work overload, a deteriorating sense of status and recognition, and unsatisfactory interpersonal relationships. The implications of the study are discussed in terms of both individual and organizational factors.
THE OVER‐STATED CASE OF EDUCATOR STRESS
Authors: MILSTEIN MIKE , FARKAS JAMES
Published: February 2008

The main body of literature that has developed about educator stress indicates ours is a profession marked by high levels of distressful encounters and that educators are not faring well in this environment. The authors believe this case is over‐stated and that education, as a field, is not nearly so marked by the littered casualties of distress that the literature would have us believe exist. This conclusion is founded on both a small literature base which holds a contrary point of view, and on three studies of administrators and teachers which consistently indicate educators are much more adaptable and consequently, less stressed, than we have been led to believe. The purpose of the first study was to identify the levels of stress school principals experience on the job and to investigate the impact of perceived locus of control and powerlessness on their stress levels. The second study examined the extent to which school principals' perceived level of stress is related to their role relationship with groups internal and external to the school organization. The goals of the third study were to establish the levels of teachers' perceived stress, the organizationally‐based factors that are most stress‐inducing, and the predominant ways in which teachers manifest stress. The results of these studies, with great consistency, indicate low educator stress. These findings have important implications for the development of new approaches to stress research and for policy decisions concerning allocation of organizational resources to stress management design and staff development.
ADMINISTRATION IN LESS DEVELOPED COUNTRIES: CONSIDERATIONS FOR EDUCATORS
Authors: DOUGLAS ANNE
Published: February 2008

In order to guide the effective administration of an organization in an unfamiliar culture, it is incumbent on the educational administrator to become responsive to the new environment and initiate correspondingly appropriate administrative practices. A review of literature from management, administration and intercultural communication suggests a conceptual approach useful to the western trained educational administrator working in a less developed country. Practices which prove effective and are taken for granted in the administrator's native culture may prove ineffective or dysfunctional when applied elsewhere. On the other hand, practices that prove to be the most effective for a given cultural environment may appear either contradictory or counterproductive to the western trained administrator. Further, administrators may approach their new responsibilities from within a framework of norms and values which are in conflict with, or unrelated to those of the new environment. Existing societal conditions may present challenges to western bureaucratic models resulting in a discrepancy between formal power and actual power. Traditional status and authority bases contribute to differing concepts of participation, specialization, loyalty and motivation, as well as the degree to which an organization can tolerate decentralization. Although historically cultural dominance models guided cross‐cultural administration, initiatives and exchanges depend increasingly on mutual understanding and acceptance. The concept of cultural synergy suggests an interactive administrative model combining elements from two or more cultures and resulting in more effective and relevant outcomes.
Profile of Excellence: Thomas J. Sergiovanni
Authors: Radford Lillian
Published: February 2008

To be a student and reader in the areas of educational administration or organisational leadership has, in the last ten years, necessitated constant exposure to the name Sergiovanni. Prolific writer, gifted teacher, creative researcher and caring mentor are all terms applied to this gentle American, born of Italian parents in New Rochelle, New York.
GAS FLOWS WITHIN TURNING SECTIONS
Authors: PLATFOOT R. , FLETCHER C.A.J.
Published: February 2008

An alternative algorithm has been developed for computing the behaviour of flows within arbitrary ducts and channels. This technique requires a small number of downstream marches in the primary flow direction, employing, on each march, numerically efficient procedures originally developed for a single sweep non‐elliptic flow solver. The multiple sweeps allow the capture of effects such as upstream pressure influences and streamwise recirculation. The energy equation is also solved to allow for varying heat transfer between the fluid and the boundary walls. The numerical work is further complicated by considering flows within turning sections of ducts which demonstrate large transverse velocities and consequent distortion of the primary flow. The computations are validated by comparison with a number of fluid/heat transfer experiments. The majority of these are taken from studies of turning flows within circular arc ducts which display the various pressure and transverse flow phenomena for which this new algorithm was initially developed to represent.
MULTIGRID SOLUTION OF STEADY EULER EQUATIONS BASED ON POLYNOMIAL FLUX‐DIFFERENCE SPLITTING
Authors: DICK ERIK
Published: February 2008

A flux‐difference splitting based on the polynomial character of the flux vectors is applied to steady Euler equations, discretized with a vertex‐centred finite volume method. In first order accurate form, a discrete set of equations is obtained which is both conservative and positive. Due to the positivity, the set of equations can be solved by collective relaxation methods in multigrid form. A full multigrid method based on successive relaxation, full weighting, bilinear interpolation and W‐cycle is used. Second order accuracy is obtained by the Chakravarthy‐Osher flux‐extrapolation technique, using the Roe‐Chakravarthy minmod limiter. In second order form, direct relaxation of the discrete equations is no longer possible due to the loss of positivity. A defect‐correction is used in order to solve the second order system.
A FRACTIONAL STEP FINITE ELEMENT METHOD FOR CONDUCTIVE‐CONVECTIVE HEAT TRANSFER PROBLEMS
Authors: HATANAKA KATSUMORI , KAWAHARA MUTSUTO
Published: February 2008

A new fractional step method in conjunction with the finite element method is proposed for the analysis of the thermal convection and conduction in a fluid region expressed by the momentum equations, the equation of continuity and the energy equation. This paper focuses on the features of the present finite element method which gives a simple way of treating the Neumann boundary condition for the pressure Poisson equation. The applicability and effectiveness of the proposed scheme are illustrated through the numerical examples of the two‐dimensional natural convection flow in enclosures with several Rayleigh numbers.
FINITE ELEMENT—ALGEBRAIC CLOSURE MODELLING OF TURBULENT SEPARATED FLOW OVER A BACKWARD‐FACING STEP: STEADY AND UNSTEADY ASPECTS
Authors: QIN ZHONG , OLSON
Published: February 2008

A numerical method is developed for steady and unsteady turbulent flows with significant regions of separation. A finite element formulation of the Navier‐Stokes equations with a modified Baldwin‐Lomax eddy viscosity closure is used. The method of averaging is employed to obtain a periodic solution of unsteady flow. The formulation is tested on a problem of flow over a backward‐facing step and the results are compared with experimental and other numerical results. The gross features of both steady and unsteady flows are reasonably well predicted by the numerical analysis, at least for the limited range of parameters tested so far.
HYBRID ANALYSIS OF TRANSIENT NON‐LINEAR CONVECTION‐DIFFUSION PROBLEMS
Authors: SERFATY R. , COTTA R.M.
Published: February 2008

A hybrid numerical‐analytical approach, based on recent developments in the generalized integral transform technique, is presented for the solution of a class of non‐linear transient convection‐diffusion problems. The original partial differential equation is integral transformed into a denumerable system of coupled non‐linear ordinary differential equations, which is numerically solved for the transformed potentials. The hybrid analysis convergence is illustrated by considering the one‐dimensional non‐linear Burgers equation and numerical results are presented for increasing truncation orders of the infinite ODE system.
GAS FLOW IN A SINGLE CYLINDER INTERNAL COMBUSTION ENGINE: A MODEL AND ITS NUMERICAL TREATMENT
Authors: ENGL GABRIELE , RENTROP PETER
Published: February 2008

We present results of a mathematical model for the gas flow in an internal combustion engine consisting of a single cylinder with an inlet and outlet pipe. In order to achieve optimal performance of the engine the dependence of the gas flow on physical parameters such as pipe dimensions and valve geometry need to be understood. A system of ordinary differential equations (in time t) with discontinuous right‐hand side describes the gas properties in the cylinder, whereas the gas flow in each pipe is modelled by the Euler equations, a system of hyperbolic partial differential equations. The explicit method of Euler and a TVD scheme are used for solving these equations. However, since the coupling of the pipe equations with the o.d.e. system in the cylinder on one side and atmospheric gas properties on the other appeared to be a main problem, we concentrate on appropriate coupling conditions. The numerical techniques involve discretization in space and time, and we present different methods of discrete coupling. As a main result we show that the various coupling methods lead to quite different numerical solutions. Therefore, a careful treatment of the coupling conditions is crucial.
STABILITY OF NON‐SIMILAR SHEAR LAYERS
Authors: MACARAEG M.G.
Published: February 2008

The present study is concerned with the stability and transition of a spatially evolving wake emanating from a splitter plate. Temporal linear stability calculations at different streamwise locations indicate significantly higher growth rates for mean flow profiles which occur near the trailing edge. Spatial simulations using these near wake mean flows exhibit non‐linear roll‐up for a case with Mach numbers of 2.76 and 1.87 on either side of the wake. If a similarity shear layer mean flow profile with these conditions is utilized in the simulation, no roll‐up is obtained.
AN EFFICIENT PROCEDURE FOR FINDING THE STEADY STATE SOLUTION OF CYCLIC, LINEAR, DISCRETE SYSTEMS
Authors: LOMBARD C. , MATHEWS E.H.
Published: February 2008

A general numerical method for finding the steady state solution of a cyclic system is presented. The method determines the initial values by enforcing the conditions of periodicity. In this way the initial value is found by integrating through only one cycle, often resulting in a considerable saving of computing effort. The method is applicable to any linear discrete set of difference equations with periodic parameters and forcing functions. The application of the method to a single pole representation of heat flow in buildings is demonstrated.
FAST MULTIGRID METHOD FOR 3‐D TURBULENT INCOMPRESSIBLE FLOWS
Authors: BAI XUE‐SONG , FUCHS LASZLO
Published: February 2008

The averaged Navier‐Stokes and the k‐e turbulence model equations are used to simulate turbulent flows in some internal flow cases. The discrete equations are solved by different variations of Multigrid methods. These include both steady state as well as time dependent solvers. Locally refined grids can be added dynamically in all cases. The Multigrid schemes result in fast convergence rates, whereas local grid refinements allow improved accuracy with rational increase in problem size. The applications of the solver to a 3‐D (cold) furnace model and to the simulation of the flow in a wind tunnel past an object prove the efficiency of the Multigrid scheme with local grid refinement.
FINITE ELEMENT ANALYSIS OF STIRRING INDUCED BY AN ALTERNATING MAGNETIC FIELD
Authors: BERELOWITZ M. , BAR‐YOSEPH P.
Published: February 2008

The numerical investigation into the stirring induced by an alternating magnetic field, applied in the axial direction of a closed axisymmetric container of conducting fluid, is presented. The interaction between the azimuthal current and magnetic field results in Lorentz forces in the meridional plane which induce the fluid flow. The magnetic Reynolds number is assumed to be smaller than the frequency magnetic Reynolds number. The electromagnetic equations are thus decoupled from the fluid flow equations. The electromagnetic field is first solved, and the body forces determined from this are introduced into the Navier‐Stokes equations. With the flow field known, the quality of mixing is determined by solving the tracer dispersion equation. The finite element method based on a Galerkin formulation is used for the solution of the equations. Three cases are examined: a finite length cylinder, a finite length cylinder with rounded corners and a sphere. In general, two vortices are formed, the equatorial vortex closest to the equator and the end vortex at the closed end. Results show that the introduction of the rounded corner increases the size and strength of the end vortex with the opposite effect on the equatorial vortex. Of the three frequency magnetic Reynolds numbers considered (Rw=30, 100 and 800), Rw=100 results in the best mixing for all cases. Rounding the corner of the cylinder only results in a definite improvement of mixing at Rw=800. The sphere results in even better mixing than this at Rw=800, but is worse than the first two geometries for Rw=30 and 100 when the interaction parameter is large.
ADAPTIVE GRID METHOD FOR UNSTEADY FLOW PROBLEMS
Authors: BOCKELIE MICHAEL J. , EISEMAN PETER R.
Published: February 2008

An adaptive grid solution method is described for computing the time accurate solution of an unsteady flow problem. The solution method consists of three parts: a grid point redistribution method; an unsteady Euler equation solver; and a temporal coupling routine that links the dynamic grid to the flow solver. The grid movement technique is a direct curve by curve method containing grid controls that generate a smooth grid that resolves the severe solution gradients and the sharp transitions in the solution gradients. By design, the temporal coupling procedure provides a grid that does not lag the solution in time. The adaptive solution method is tested by computing the unsteady inviscid solutions for a one‐dimensional shock tube and a two‐dimensional shock vortex interaction. Quantitative comparisons are made between the adaptive solutions, theoretical solutions and numerical solutions computed on stationary grids. Test results demonstrate the good temporal tracking of the solution by the adaptive grid, and the ability of the adaptive method to capture an unsteady solution of comparable accuracy to that computed on a stationary grid containing significantly more grid points than used in the adaptive grid.
DIRECT SPECTRAL METHODS FOR THE LOW MACH NUMBER EQUATIONS
Authors: FRÖHLICH J. , PEYRET R.
Published: February 2008

The low Mach number approximation of the Navier—Stokes equations is of similar nature to the equations for incompressible flow. A major difference, however, is the appearance of a space‐ and time‐varying density that introduces a supplementary non‐linearity. In order to solve these equations with spectral space discretization, an iterative solution method has been constructed and successfully applied in former work to two‐dimensional natural convection and isobaric combustion with one direction of periodicity. For the extension to other geometries efficiency is an important point, and it is therefore desirable to devise a direct method which would have, in the best case, the same stability properties as the iterative method. The present paper discusses in a systematic way different approaches to this aim. It turns out that direct methods avoiding the diffusive time step limit are possible, indeed. Although we focus for discussion and numerical investigation on natural convection flows, the results carry over for other problems such as variable viscosity flows, isobaric combustion, or non‐homogeneous flows.
SOLUTIONS OF SOME AXISYMMETRIC LOW STEFAN NUMBER MELTING PROBLEMS BY AN IMPROVED FINITE DIFFERENCES METHOD
Authors: SOKOLOV M. , KEIZMAN Y.
Published: February 2008

The use of explicit finite difference schemes for low Stefan number problems with moving interface was largely abandoned because they require small time intervals (large CPU time) to obtain accurate non‐oscillatory solutions. This paper uses these type of schemes for better estimations of the dynamics of the solid—liquid interface. The scheme in which time and radial intervals are constant, uses a local, continuous, time‐dependent radial coordinate to define the instantaneous location of the interface. Taylor series expansions which result in a polynomial fit are used for forward and backward interpolation of temperatures of nodal points in the vicinity of the interface. A distinction is made between the left and right position of the interface relative to the closest nodal point. The algorithm handles accurately and effectively the non‐linearities near the interface thus producing accurate stable solutions with relatively low CPU time. The scheme which obviously may be applied to large Stefan number problems, is also suitable for time dependent boundary conditions as well as temperature dependent physical properties. The results obtained by the scheme were in excellent agreement with ones derived from an approximate analytical solution which is applicable in the low Stefan number range.
A FINITE ELEMENT EIGENVALUE METHOD FOR SOLVING TRANSIENT HEAT CONDUCTION PROBLEMS
Authors: ZHONG JIAKANG , CHOW LOUIS C. , SOON CHANG WON
Published: February 2008

An eigenvalue method is presented for solving the transient heat conduction problem with time‐dependent or time‐independent boundary conditions. The spatial domain is divided into finite elements and at each finite element node, a closed‐form expression for the temperature as a function of time can be obtained. Three test problems which have exact solutions were solved in order to examine the merits of the eigenvalue method. It was found that this method yields accurate results even with a coarse mesh. It provides exact solution in the time domain and therefore has none of the time‐step restrictions of the conventional numerical techniques. The temperature field at any given time can be obtained directly from the initial condition and no time‐marching is necessary. For problems where the steady‐state solution is known, only a few dominant eigenvalues and their corresponding eigenvectors need to be computed. These features lead to great savings in computation time, especially for problems with long time duration. Furthermore, the availability of the closed form expressions for the temperature field makes the present method very attractive for coupled problems such as solid—fluid and thermal—structure interactions.
HEAT SOURCES AND TEMPERATURE DISTRIBUTION IN INSULATED GATE BIPOLAR TRANSISTORS
Authors: BOARD K. , MAWBY P.A.
Published: February 2008

The insulated gate bipolar transistor (IGBT) is an increasingly used power transistor which has the advantage over the more conventional DMOS structure of achieving a lower on‐resistance through the high‐injection of electrons and holes into the drift region thereby causing conductivity modulation and a lowering of the electrical resistance.
HEAT AND FLUID FLOW AT ENTRANCE REGIONS OF ROTATING ISO‐HEAT FLUX CHANNELS WITH LAMINAR THROUGHFLOW
Authors: FANN SHIN , YANG WEN‐JEI , MOCHIZUKI S.
Published: February 2008

A theoretical study is performed on three‐dimensional, heat transfer and fluid flow in radially rotating heated channels with steady, laminar throughflow. Consideration is given to the channel of different geometry. Both the rotational speed and throughflow rate are varied. The flow is hydrodynamically and thermally developing, with a constant wall heat flux. The velocity‐vorticity method is employed in the formulation and numerical results are obtained by means of a finite‐difference technique. The Nusselt number, friction factor, and temperature and velocity distributions are determined, and the role of the Coriolis force on the entrance‐region transport phenomena is investigated. Results are compared with the existing literature.
FLOW OF THE POWER‐LAW FLUID IN THE INLET REGION OF A DUCT WITH BLOWING OR SUCTION
Authors: HUNG C.I. , PERNG Y.Y.
Published: February 2008

The hydrodynamic development of non‐Newtonian fluid flow in the entrance region of a duct with porous walls is examined numerically by solving the modified Navier‐Stokes equations. Cases involving blowing, suction, and no mass transfer through the walls are considered. Velocity distributions, pressure drops, and skin friction coefficients are presents for each case. A definite concavity is found in the velocity profile near the duct entrance for all cases. Results for Newtonian fluids are compared with previous studies in which boundary‐layer theory was used. In the region away from the entrance it is found that the present results are in good agreement with previous works. In the region close to the entrance, or in the case of suction, boundary‐layer theory is shown to be inappropriate.
FULLY DEVELOPED LAMINAR FLUID FLOW AND HEAT TRANSFER IN A STREAMWISE‐PERIODIC CORRUGATED DUCT WITH CONSTANT CROSS‐SECTIONAL AREA
Authors: FARHANIEH BIJAN , SUNDÉN BENGT
Published: February 2008

Laminar fully developed periodic heat transfer and fluid flow characteristics in corrugated two‐dimensional ducts with constant cross‐sectional area are numerically investigated. The governing equations are solved numerically by a finite‐volume method for elliptic flows in complex geometries using colocated variables and Cartesian velocity components. The results were obtained for a uniform wall temperature for two inclination angles and three duct aspect ratios (H/L) and for Reynolds number ranging from 30 to 1200. The plot of the velocity vectors show a complex flow pattern. Unexpected high enhancement of the average Nusselt number was observed at low Reynolds number for H/L = ½ and ⅓. A moderate increase in Nusselt number was obtained as Reynolds number was increased further.
ULTRA‐SHARP SOLUTION OF THE SMITH‐HUTTON PROBLEM
Authors: LEONARD B.P. , MOKHTARI SIMIN
Published: February 2008

In 1982, Smith and Hutton published comparative results of several different convection‐diffusion schemes applied to a specially devised test problem involving near‐discontinuities and strong streamline curvature. First‐order methods showed significant artificial diffusion, whereas higher‐order methods gave less smearing but had a tendency to overshoot and oscillate. Perhaps because unphysical oscillations are more obvious than unphysical smearing, the intervening period has seen a rise in popularity of low‐order artificially diffusive schemes, especially in the numerical heat‐transfer industry. This paper presents an alternative strategy of using non‐artificially diffusive higher‐order methods, while maintaining strictly monotonic transitions through the use of simple flux‐limiter constraints. Limited third‐order upwinding is usually found to be the most cost‐effective basic convection scheme. Tighter resolution of discontinuities can be obtained at little additional cost by using automatic adaptive stencil expansion to higher order in local regions, as needed.
THREE‐DIMENSIONAL SIMULATION OF THE HEAT TRANSFER AND TEMPERATURE DISTRIBUTION IN A LIQUID GAS TANK
Authors: VISSER J.A. , ROLFES H.
Published: February 2008

By modelling the unsteady heat transfer in liquid gas tanks, the temperature distribution in the tank as well as the heat flux reaching the liquid gas can be predicted. Knowledge of the temperature distribution and heat flux can be used to predict evaporation losses from the tank. By minimizing the evaporation losses, the thermal design of a gas tank can be optimized. This paper presents a finite difference simulation of the unsteady three‐dimensional heat transfer in gas tanks and an optimized configuration. The numerical procedure accounts for radiation from the sun as well as radiative and convective heat transfer with the environment. A non‐uniform grid is used because the tank consists of several different materials of varying dimensions and properties. Geometrical effects such as variations in the thickness of the insulation material and the diameter and height of the tanks are also studied in an attempt to optimize the design configuration.
SOLUTION OF INCOMPRESSIBLE NAVIER‐STOKES EQUATIONS ON UNSTRUCTURED GRIDS USING DUAL TESSELLATIONS
Authors: CAVENDISH J.C. , HALL C.A. , PORSCHING T.A.
Published: February 2008

We describe a novel mathematical approach to deriving and solving covolume models of the incompressible 2‐D Navier‐Stokes flow equations. The approach integrates three technical components into a single modelling algorithm: 1. Automatic Grid Generation. An algorithm is described and used to automatically discretize the flow domain into a Delaunay triangulation and a dual Voronoi polygonal tessellation. 2. Covolume Finite Difference Equation Generation. Three covolume discretizations of the Navier‐Stokes equations are presented. The first scheme conserves mass over triangular control volumes, the second scheme over polygonal control volumes and the third scheme conserves mass over both. Simple consistent finite difference equations are derived in terms of the primitive variables of velocity and pressure. 3. Dual Variable Reduction. A network theoretic technique is used to transform each of the finite difference systems into equivalent systems which are considerably smaller than the original primitive finite difference system.
A TRANSIENT FINITE ELEMENT ADAPTATION SCHEME FOR THERMAL PROBLEMS WITH STEEP GRADIENTS
Authors: RAMAKRISHNAN R. , WIETING ALLAN R. , THORNTON EARL A.
Published: February 2008

An adaptive mesh refinement procedure that uses nodeless variables and quadratic interpolation functions is presented for analysing transient thermal problems. A temperature based finite element scheme with Crank‐Nicolson time marching is used to obtain the thermal solution. The strategies used for mesh adaptation, computing refinement indicators, and time marching are described. Examples in one and two dimensions are presented and comparisons are made with exact solutions. The effectiveness of this procedure for transient thermal analysis is reflected in good solution accuracy, reduction in number of elements used, and computational efficiency.
AN ALGEBRAIC MULTIGRID SOLVER FOR THE NAVIER—STOKES EQUATIONS ON UNSTRUCTURED MESHES
Authors: LONSDALE R.D.
Published: February 2008

A simple algebraic multigrid (AMG) solver for linear equations is presented, and its performance compared with a conjugate gradient scheme. This multigrid method is extended to solve the discrete Navier—Stokes equations, obtained by applying a finite volume approach to three‐dimensional incompressible flow on a finite element mesh. The resulting multigrid solver is incorporated into a general purpose flow code (ASTEC), where it proves faster than the original solution algorithm, based upon SIMPLE. The linear AMG solver is both efficient and robust, but the extension to include coupling in the Navier—Stokes equations does not converge on all problems.