bluuebunny/crossref_metadata_2025 huggingface dataset:
The Use of Landmarks in Fire Emergencies: A Study of Gender and the Descriptive Quality of Landmarks on Successful Wayfinding
Authors: Jung Jin Woo , Gibson Kathleen
Published: June 2008

Researchers reviewing fire conditions at the Coconut Grove Night Club and the Beverly Hills Supper Club found occupant behavior was a factor in loss of life (Chertkoff & Kushigian, 1999). For this study, a virtual environment (VE) was created and subjects were randomly assigned to experience one of six virtual reality (VR) simulations. Wayfinding performance was scored on a four point scale: no errors, errors with self–recovery, errors requiring re–reading to recover, and failure to reach an exit. Subjects’ responses to survey questions were statistically analyzed against their VR performance using ANOVA and Chi–Square. Sixty–nine 1 8–24 year old college students (female N = 37; male N = 32) served as the sample population. Results suggest that the describability of landmarks provided a positive influence to route communication. Post hoc analyses revealed that participants using describable landmarks (DL) had a significantly lower (faster) total time than those with no landmarks (NL). Several gender relationships were found in this study. In the NL condition, males re–read less frequently compared to females; while males re–read in greater proportion than females in the non–describable landmark (NDL) condition. In the NL condition, females visited more sub–areas than males; whereas females visited fewer sub–areas in the DL and NDL conditions. This study provides valuable conclusions about wayfinding that can be applicable in the design of schools, dormitories, and other facilities used primarily by young adults.
Knowledge on Knowledge
Authors: Blackmer Bruce E.
Published: June 2008

Bruce E. Blackmer, FAIA, is President and CEO of Northwest Architectural Company, a firm of 120 specializing in architecture, planning, interior design, and capital facilities consulting, with offices in Seattle and Spokane, Washington, and Coeur d̂Alene, Idaho. With market focus in education, healthcare, laboratory, biotechnology, recreation, civic, hospitality, and extended care facilities, Northwest Architectural Company has been recognized internationally, with London–based World Architecture ranking the firm 178th in the world for 2004. Bruce was instrumental in developing the American lnstitute of Architects’ initiative to become a knowledge organization. He was a leading advocate for the knowledge agenda during his 1999–2002 term on the AIA National Board, and as Vice–President of the Institute in 2003, he spearheaded the reengineering of the former Professional lnterest Areas into the current AIA Knowledge Communities. Bruce received his Bachelor of Architecture degree from North Dakota State University and Master of Business Administration degree from Gonzaga University. He is a licensed architect in five states, NCARB certified, a past Regent of the American Architectural Foundation, and incoming Director of the National Architectural Accreditation Board.
Understanding the Plan: A Studio Experience
Authors: Hing Allan
Published: June 2008

The plan is a powerful tool in the design process that requires both intellectual and creative rigor. The focus of this article is the methodology of how the plan is presented, developed, and understood in sophomore interior design studio. The studio's goal is to give students a foundation of understanding by broadening their knowledge of spatial design through the study of the plan and plan language. The plan is what architects and interior and landscape designers use to move people through space, to organize space, and to place objects in space.

The article outlines how this material is presented through readings, lectures, and design projects. The lessons require students to be creative and analytical in developing a plan, to gain visual literacy in understanding a plan and its spaces, and to use plan language in their explanations in studio. Students should learn to think and speak in terms of entry, path, and goal. Plan language includes such terms as axis, centering and re–centering, symmetry, focal points, gesturing, reinforcement, in–line, articulation, and hierarchy.

Students are required to take a letterform and develop an orchestrated spatial walk through the form using plan language, and then they must complete a series of diagrams. Past and present plan types are analyzed and important architects who have contributed to the plan and plan language are discussed (Mackintosh, Wright, Le Corbusier, and Scarpa).

The plan is the element which most interior designers use to develop space. Therefore, students and educators should have a greater understanding and vocabulary for such an important tool.
Interior Design in K–12 Curricula: Asking the Experts
Authors: Clemons Stephanie A.
Published: June 2008

The purpose of this qualitative study was to assess how interior design content areas (subject matter) could be introduced and integrated into elementary and secondary (K–12) grade levels in support of national academic education standards. Although the minimum standards have been developed for entry level interior designers (Council for Interior Design Accreditation [CIDA] Standards, adopted 2002) and beyond (National Council for Interior Design Qualification [NCIDQ]), a gap exists in the interior design education continuum from “kindergarten to career.”

Between June 2001 to April 2002, in order to understand perceptions of experts in interior design and elementary and secondary education, focus group sessions and personal interviews were conducted with interior design educators and practitioners, K–12 teachers (elementary, junior high, and high school levels), national standards curriculum specialists (local and state levels), and school–to–career curriculum specialists. The goal of the study was to develop a framework that could guide the integration of interior design content into K–12 levels.

This paper reports the findings from the focus groups and proposes a framework that could guide the national integration of interior design content into grades K–12, support national academic standards, and suggest possible channels of dissemination for developed interior design curriculum materials.
A Case for a Typology of Design: The Interior archetype Project
Authors: Jennings Jan
Published: June 2008

The “Interior Archetypes Research and Teaching Project”, initiated in 1997 at Cornell University, creates a typology of contemporary interior design practices that is derived from reiterative historical designs that span time and style and cross cultural boundaries. An argument for the significance of a typology of historic and contemporary interior design practices is based on ten years of experiments resulting from the project. Approximately one hundred archetypes have been developed by the principal investigator, graduate students, and associated educators. The article establishes the premises for this research model and defines the methodological, theoretical, and pedagogical implications of the study for both undergraduate and graduate learning experiences. The Interior Archetypes Project names contemporary design practices that have not been named, thereby providing designers with an interior–specific, history–specific, and contemporary design–specific vocabulary. The project also offers an innovative approach to further design criticism and design sustainability. The Interior Archetypes Project will disseminate a new knowledge base for the creative dimension of design—that is, the productions of its practitioners. The key method of delivery for the Interior Archetypes Project is its web site.
Perspective: A Method for Uniform Reporting of Grid Refinement Studies
Authors: Roache P. J.
Published: May 2008

This paper proposes the use of a Grid Convergence Index (GCI) for the uniform reporting of grid refinement studies in Computational Fluid Dynamics. The method provides an objective asymptotic approach to quantification of uncertainty of grid convergence. The basic idea is to approximately relate the results from any grid refinement test to the expected results from a grid doubling using a second-order method. The GCI is based upon a grid refinement error estimator derived from the theory of generalized Richardson Extrapolation. It is recommended for use whether or not Richardson Extrapolation is actually used to improve the accuracy, and in some cases even if the conditions for the theory do not strictly hold. A different form of the GCI applies to reporting coarse grid solutions when the GCI is evaluated from a “nearby” problem. The simple formulas may be applied a posteriori by editors and reviewers, even if authors are reluctant to do so.
A Correction Formula for Wall Effects on Unsteady Forces of Two-Dimensional Bluff Bodies
Authors: Ota Terukazu , Okamoto Yasunori , Yoshikawa Hiroyuki
Published: May 2008

In wind tunnel studies on the flow around bluff bodies accompanying a large separated wake, the walls of the test section severely effect the flow characteristics around them. Proposed in this paper is a correction formula for the wall effects upon two-dimensional (2-D) unsteady separated flow of incompressible fluid around bluff bodies. The proposed formula is derived from numerical results with the discrete vortex method on 2-D separated flows around an inclined flat plate, a square cylinder, and also an elliptic cylinder located between two parallel walls. It is found that the present correction formula estimates reasonably well the wall effects upon the mean and fluctuating force coefficients over a wide range of blockage ratio and angle of attack through comparing the present calculated results with numerous experimental ones by several authors.
A Small Wind Tunnel Significantly Improved by a Multi-Purpose, Two-Flexible-Wall Test Section
Authors: Kankainen P. , Brundrett E. , Kaiser J. A.
Published: May 2008

A small open-return wind tunnel has been renovated to include a longer test section with a flexible roof and floor and improved entrance flow quality. The flexible-wall test section allows models with up to 30 percent nominal blockage to be tested, resulting in a significant increase in the maximum attainable Reynolds numbers. Interchangeable rigid side-wall panels allow flexibility of application which is essential for a university wind tunnel facility. Configurations have been developed for automotive, aerodynamic and atmospheric-boundary-layer testing. Data acquisition and wall positioning are at an economical semi-automated level of operation. The flexible-wall concept has been well-documented previously, and provides interference-free data without flow pattern assumptions after a few iterations of the roof and floor shape. Representative data are presented for a circular cylinder and an airfoil.
On the Unsteady and Turbulent Characteristics of the Three-Dimensional Shear-Driven Cavity Flow
Authors: Jordan S. A. , Ragab S. A.
Published: May 2008

The three-dimensional shear-driven cavity flow is numerically investigated at Reynolds numbers of 5000 and 10000. This investigation focuses on the unsteadiness and turbulent characteristics of the flow. At the moderate Reynolds number (Re = 5000) where the cavity flow is fully laminar, a direct numerical simulation (DNS) is used whereas large-eddy simulation (LES) methodology is adopted to predict the cavity flow at the higher Reynolds number (Re = 10000). Establishing a suitable form for the subgrid scale (SGS) turbulence model in this complex flow is guided by the DNS results at Re = 5000. Additionally, the SGS model is verified against DNS results at Re = 7500 where the cavity flow is known through experimentation to be locally transitional. The LES results verify the published experimental evidence as well as uncover new flow features within the cavity.
The Minimum Drag Profile in Laminar Flow: A Numerical Way
Authors: Ganesh Ram K.
Published: May 2008

It would be of interest to engineers and scientists to know the shape of the body of a given volume that will have minimum drag when moving through a viscous fluid at constant speed. It would be extremely useful if one could devise an evolution procedure that can evolve the minimum drag body in a logical and an orderly manner. Such a procedure was suggested by Pironneau for laminar flow wherein optimality conditions derived using optimal control theory were used in a non-linear gradient algorithm. The literature cites an attempt of the procedure at high Reynolds number where for each iteration in the evolution process, the flow field required an outer and an inner solution and the calculation of the gradient optimality condition required the solution of the co-state equation, a type of boundary layer equation. This paper addresses the direct simulation of the governing elliptic partial differential equations, viz., the Navier-Stokes and the co-state equations. Even though the latter has no simple mechanical interpretation, capitalizing on its resemblance to the former, this paper shows how the solution to the co-state equation could be obtained by simply adapting an existing Navier-Stokes code. Solution of the flow field and the calculation of the necessary criteria required in the evolution process are also discussed. The novelty of this direct approach is to make the evolution process more general, arbitrary and less complex. The profile evolution is demonstrated for flows at different Reynolds numbers.
Experimental Determination of Transition to Turbulence in a Rectangular Channel With Eddy Promoters
Authors: Kapat J. S. , Ratnathicam J. , Mikic´ B. B.
Published: May 2008

We report on laminar-to-turbulent transition in a rectangular channel in the presence of periodically placed cylindrical eddy promoters. Transition is identified through the analysis of power spectral density (PSD) of velocity fluctuations. Placement of the eddy promoters in the channel, depending on the geometric configuration, can significantly reduce the value of Reynolds number at transition. The critical Reynolds number (based on the average velocity and the channel height) ranges from 1500 (for an unobstructed channel) to about 400 (for the most unstable configuration we have deployed). For all the configurations tested, demarcation of transition can be correlated with the expression: Reτ≡τ¯w,αv/ρH/2/ν=44˜51, where τw,αv is the spatially averaged value of mean wall shear stress and H is the channel height.
Friction Factor for Flow in Rectangular Ducts With One Side Rib-Roughened
Authors: Youn B. , Yuen C. , Mills A. F.
Published: May 2008

Numerical simulations of incompressible turbulent flow through rectangular ducts with one side rib-roughened were performed to determine pressure drop. The “PHOENICS” software package was used for the computations, which required provision of a wall function for transverse rib-roughened surfaces. The present study was conducted in the range of 105≤ Reynolds number ≤ 107, 0.01 ≤ rib height to hydraulic diameter ratio ≤ 0.04, 10≤ pitch to rib height ratio ≤ 40. Using the numerical results, friction factor charts for various aspect ratios were generated. The numerical results agreed well with experimental data that was obtained for 105 < Reynolds number < 2 × 105. In addition, a scheme for predicting friction factor using existing correlations for smooth and rough walls was developed.
Time-Dependent Conjugate Heat Transfer Characteristics of Self-Sustained Oscillatory Flows in a Grooved Channel
Authors: Nigen J. S. , Amon C. H.
Published: May 2008

Convective heat transport in a grooved channel is numerically investigated using a time-dependent formulation. Conjugate conduction/convection and uniform heat-flux representations for the solid domain are considered. For the conjugate representation, the solid domain is composed of multiple materials and concentrated heat generation. The associated cooling flows include laminar and transitional regimes. Steady and time-dependent contours of the streamfunction and local skin-friction coefficients are presented. Additionally, local distributions of Nusselt number and surface temperature are displayed for both the conjugate and convection-only representations. These results are contrasted over the range of Reynolds numbers explored to demonstrate the significance of including time-dependency and conjugation in the study of convective heat transport. Such considerations are found to be important in the design and analysis of heat exchanger configurations with spatially varying material composition and concentrated heat generation.
Evaluation of Flip-Flop Jet Nozzles for Use as Practical Excitation Devices
Authors: Raman Ganesh , Rice Edward J. , Cornelius David M.
Published: May 2008

This paper describes the flowfield characteristics of the flip-flop jet nozzle and the potential for using this nozzle as a practical excitation device. It appears from the existing body of published information that there is a lack of data on the parameters affecting the operation of such nozzles and on the mechanism of operation of these nozzles. An attempt is made in the present work to study the important parameters affecting the operation and performance of a flip-flop jet nozzle. Measurements were carried out to systematically assess the effect of varying the nozzle pressure ratio (NPR) as well as the length and volume of the feedback tube on the frequency of oscillation of this device. Flow visualization was used to obtain a better understanding of the jet flowfield and of the processes occurring within the feedback tube. The frequency of oscillation of the flip-flop jet depended significantly on the feedback tube length and volume as well as on the nozzle pressure ratio. In contrast, the coherent velocity perturbation levels did not depend on the above-mentioned parameters. The data presented in this paper would be useful for modeling such flip-flop excitation devices that are potentially useful for controlling practical shear flows.
A Correlation of Leakage Vortex Cavitation in Axial-Flow Pumps
Authors: Farrell K. J. , Billet M. L.
Published: May 2008

Tip clearance flow in turbomachinery can lead to losses in efficiency and stall margin. In liquid handling turbomachinery, the vortical flow field, formed from the interaction of the leakage flow with the through-flow, is subject to cavitation. Furthermore, this flow field is complex and not well understood. A correlation of variables which predict the vortex minimum pressure has been formulated. Measurements of the important variables for this correlation have been made on a high Reynolds number (3 × 106) axial-flow test rig. The correlation has been applied to the measured data and other data sets from the literature with good agreement. An optimum tip clearance has been theoretically identified as experiments have shown. Observations of cavitation indicate a second vortex originating along the suction side trailing edge.
Thermal Choking Due to Nonequilibrium Condensation
Authors: Guha Abhijit
Published: May 2008

A theory of thermal choking due to nonequilibrium condensation in a nozzle is presented. An explicit equation for the critical quantity of heat in condensing flow has been derived. The equation is of general validity and applies to vapor-droplet flow with or without a carrier gas. It has been usually assumed in the literature that the classical gas dynamics result for the critical quantity of heat applies in condensing flow as well. The classical result is, however, obtained by considering external heat addition to an ideal gas in a constant area duct. In this paper it is shown that the area variation across the condensation zone (although small) and the depletion in the mass of vapor as a result of condensation have profound effects on the critical quantity of heat. The present equation (derived from an integral, control-volume approach) agrees very well with results from full time-marching solution of the nonequilibrium, differential gas dynamic equations. The classical gas dynamics result, on the other hand, seriously underpredicts the critical heat for condensing flow in nozzles (by a factor of three in the example calculation presented).
Falling Needle Rheometry for General Viscoelastic Fluids
Authors: Zheng R. , Phan-Thien N. , Ilic V.
Published: May 2008

This paper reports theoretical and numerical studies on a flow of a general viscoelastic fluid past a needle placed at the centerline of a cylindrical tube, supplemented by a comparative experimental study. It is shown that the drag per unit length on the needle, which is assumed to be infinitely long, depends on the fluid viscosity only, whatever the first and second normal stress differences may be. This general theory is then specified to obtain solutions for the power-law and the Phan-Thien-Tanner fluids. The power-law fluid results provide a general technique for obtaining flow curves of non-Newtonian fluids from the measured drag forces on falling needles. This is achieved by using KU/R as the effective shear rate, where U is the terminal velocity of the needle, R is the radius of the tube, and K is a function of the power-law index n and the system geometry a/R (where a is the radius of the needle). The effect of the aspect ratio of the needle on the drag force is investigated numerically using a boundary element method for the flow of Phan-Thien-Tanner fluid. Experimentally, a flow curve was obtained for a kerosene solution of PIB (3.39 percent by weight), using falling needles of aspect ratio greater than 40 in a circular cylinder. The result compared well with Carri-Med 50 CS rheometer data.
Structure of the Mean Velocity and Turbulence in Premixed Axisymmetric Acetylene Flames
Authors: Matovic M. , Oka S. , Durst F.
Published: May 2008

Laser-Doppler measurements of axial mean velocities and the corresponding rms values of turbulent velocity fluctuations are reported for premixed, axisymmetric, acetylene flames together with the probability density distributions of the turbulent velocity fluctuations. All this information provides an insight into the structure of the flow field. Characteristic zones of the flow field are defined that show common features for all acetylene flames studied by the authors. These features are discussed in the paper and are suggested to characterize, in general, interesting parts of the flames.
Preston-Static Tubes for the Measurement of Wall Shear Stress
Authors: Ackerman Josef Daniel , Wong Louis , Ethier C. Ross , Allen D. Grant , Spelt Jan K.
Published: May 2008

We present a Preston tube device that combines both total and static pressure readings for the measurement of wall shear stress. As such, the device facilitates the measurement of wall shear stress under conditions where there is streamline curvature and/or over surfaces on which it is difficult to either manufacture an array of static-pressure taps or to position a single tap. Our “Preston-static” device is easily and conveniently constructed from commercially available regular and side-bored syringe needles. The pressure difference between the total pressure measured in the regular syringe needle and the static pressure measured in the side-bored one is used to determine the wall shear stress. Wall shear stresses measured in pipe flow were consistent with independently determined values and values obtained using a conventional Preston tube. These results indicate that Preston-static tubes provide a reliable and convenient method of measuring wall shear stress.
Natural Convection of Cold Water in a Vertical Annulus With Constant Heat Flux on the Inner Wall
Authors: Ho C. J. , Lin Y. H.
Published: May 2008

A numerical solution for steady laminar natural convection of cold water in a vertical annulus with a constant-heat-flux heated inner wall and an isothermally cooled outer wall is examined. Results are generated for flow in annuli with aspect ratio 0.5 ≤ A ≤8, the radius ratio varying between 1.2 and 10, and the density inversion parameter ranging from −2 and 1 for 103 ≤ Ra* ≤ 106. The heat and fluid flow structures of cold water are vividly visualized by means of contour maps of heatlines and streamlines. The results clearly indicate that the mixed boundary conditions considered can have a significant influence on the geometric dependence of heat transfer characteristics and fluid flow structures in comparison with those reported for isothermal boundary conditions. Multicellular flow behavior of cold water can arise in a tall annulus of A = 8.
Turbulent Mixed Convection Over an Isothermal Horizontal Flat Plate
Authors: Ramachandran N. , Armaly B. F. , Chen T. S.
Published: May 2008

Turbulent boundary layer flow adjacent to an isothermal horizontal flat plate is analyzed for the mixed convection regime. Results are presented for both air (Pr = 0.7) and water (Pr= 7) flowing above the heated plate at various velocities over a range of temperature differences between the plate and the free stream. Closure of the governing, time-averaged, turbulent equations for the mean flow quantities is attained by using a modified k–ε model that accounts for the influence of buoyancy-induced forces on the turbulent quantities. It is found that the local surface heat flux increases with increasing buoyancy force parameter. The numerical results are in qualitative agreement with available experimental measurements.
Mixed Convection on a Vertical Flat Plate With Transition and Separation
Authors: Cebeci T. , Broniewski D. , Joubert C. , Kural O.
Published: May 2008

A numerical method has been developed and used to calculate the flow properties of laminar, transitional, and turbulent boundary layers on a vertical flat plate with heat transfer. The governing boundary-layer equations include a buoyancy-force term and are solved by a two-point finite-difference method due to Keller and results obtained for heating and cooling and, in the case of the laminar flows, for an isothermal surface corresponding to that of Merkin. Cooled plates with unheated sections can give rise to boundary-layer separation and reattachment and, on occasions, transition can occur within the separation bubble. Flows of this type have been examined with the inviscid-viscous interaction procedure developed by Cebeci and Stewartson and the location of transition obtained by the en method based on the linear stability theory for air with Pr = 1. Results are given in dimensionless form as a function of Reynolds number, Richardson number, and Prandtl number and quantify those parameters that give rise to separation. Consequences of the use of interaction and stability theory are examined in detail.
Investigation of High-Intensity Beam Characteristics on Welding Cavity Shape and Temperature Distribution
Authors: Wei P. S. , Wu T. H. , Chow Y. T.
Published: May 2008

A model for investigating the characteristics of a high-intensity beam on welding cavity shape and temperature distribution is developed. The beam power density is assumed to have a Gaussian distribution. The local heat transfer rate to the liquid-vapor interface depends on this distribution and on the interface contour. This contour as determined by an iterative procedure involves simultaneously satisfying the heat conduction rate into the liquid and equilibrium of the normal forces. Computed shapes of the cavity and the free surface temperature distributions agree well with experimental data. The beam energy flux distribution parameter is found to have the strongest effect on the welding process. The predicted dimensionless curve of the beam power-penetration depth parameter versus the welding velocity-thermal property parameter is also in accord with experimental results. The use of the energy flux distribution parameter instead of the fusion zone width at the workpiece surface for the welding velocity-thermal property parameter is recommended.
Transient Plume Influence in Measurement of Convective Heat Release Rates of Fast-Growing Fires Using a Large-Scale Fire Products Collector
Authors: Yu Hong-Zeng
Published: May 2008

A theory for strongly buoyant transient plumes was used to determine whether the convective heat flow measured by a large-scale Fire Products Collector (FPC) could approximate the instantaneous convective heat release rate generated by fast-growing fires. The theory was confirmed by the plume data of rack storage fires obtained in this study. The theory provides a scheme for deriving the convective heat release rate generated at the fire source from the convective heat flow measured by the FPC.
On the Mechanism of Forced-Convection Subcooled Nucleate Boiling
Authors: Tsung-Chang G. , Bankoff S. G.
Published: May 2008

In highly subcooled nucleate boiling the bubbles grow and collapse while sliding along the heated surface, so that there is no net vapor transport away from the surface. A long-standing question exists as to whether conduction and convection between the bubbles, or latent heat transport through the bubbles, is the dominant heat transfer mechanism. It is shown here by simple calculations that the sliding of the bubble results in augmentation of microlayer evaporation under the bubble by a factor of two or more over a stationary bubble with a continuous microlayer. It appears therefore that the latent heat transport mechanism may be dominant at large bulk subcoolings.
Film Condensation on a Vertical Flat Plate in a Packed Bed
Authors: Plumb O. A. , Burnett D. B. , Shekarriz A.
Published: May 2008

Film condensation on a vertical isothermal surface submerged in a packed bed was examined experimentally. Results are presented for packed beds consisting of glass beads ranging from 350μm to 5000 μm in diameter. The condensing fluid was saturated R-11. The experimental results are compared with the theoretical results of Cheng (1981) and White and Tien (1987a). The experimental results are in poor agreement with the Cheng (1981) theory due to the effects of surface tension and variable porosity near the surface. The experimental results are in qualitative agreement with White and Tien (1987a) theory, which accounts for the wall effects. The results indicate that an improved theory that accounts for surface tension is necessary in order to achieve quantitative agreement with the experimental data.
1989 Max Jakob Memorial Award Lecture: Some Optimizing Examples in Forced Convective Heat Transfer
Authors: Mori Y.
Published: May 2008

Three examples are selected as representative cases concerning the basic convective heat transfer in the heat exchanger field, each of which has a specified parameter for optimizing the individual specific condition. First, the chemical vapor deposition of a silicone layer for SiH4 on the hot bottom wall of a horizontal rectangular furnace duct is discussed, assuming that a spatially uniform thickness of the layer is the optimal one. Second, the compact heat exchanger is studied with the insertion of a twisted strip in each channel so that the outlet temperature of the heated gas becomes uniform by changing the twist pitch appropriate to each channel. Third, a shell and helical tube heat exchanger is discussed for controlling flow-induced tube vibration by inserting separating plates between the tube arrays and optimizing the interval of the plates.
An Improved Algorithm for Inverse Design of Thermal Problems With Multiple Materials
Authors: Shau R. , Batista J. , Carey G. F.
Published: May 2008

An optimization scheme and matrix partitioning strategy are developed in conjunction with a boundary element solution procedure for inverse design in heat transfer. The optimal control problem is to locate interior heating or cooling passages inside a coated conducting domain to achieve a desired boundary temperature when the heat flux is specified (or vice versa). As the interior passages can be parameterized with a few variables, the optimization problem is of low dimension, the matrix partitioning scheme for the boundary element system and optimization search procedure lead to a fast computational scheme for this class of problems.
Thermal Behavior of Aluminum Rolling
Authors: Tseng A. A. , Tong S. X. , Maslen S. H. , Mills J. J.
Published: May 2008

Proper roll cooling has been identified as a critical factor in the problems of excessive roll spalling and poor thermal crowning in modern, high-speed rolling mills. In this paper, an analytical model has been developed to determine the temperature profiles of the roll and the strip. This model uses basic heat transfer theory and provides the capability of studying the influence of operating parameters on both the work-roll and workpiece temperatures. Examples on cold and hot rolling of aluminum alloys are given to demonstrate the feasibility and capability of the model developed. Previous work on thermal modeling of rolling processes is also briefly reviewed.
A Single-Blow Test Procedure for Compact Heat and Mass Exchangers
Authors: Van den Bulck E. , Klein S. A.
Published: May 2008

This paper discusses a single-blow test procedure for estimating the overall heat and mass transfer coefficients of compact dehumidifier matrices. The procedure consists of three sequential experimental procedures for obtaining, respectively, the core geometry of the test matrix, the active mass of sorbent within the matrix, and the distributions of the temperature and humidity ratio responses with time and distance in the flow direction. The analysis technique paired to the experimental procedure is based upon the transformation of the model partial differential equations into a set of ordinary differential equations. The temperature and mass-fraction distributions are then modeled by a system of nonstiff ordinary differential equations, which can be easily integrated numerically. The Lewis number, defined as the ratio of the overall heat to mass transfer coefficients, determines the shape of the distributions with a dimensionless flow coordinate x+. With a curve fit method, the experimental Lewis number can be determined with acceptable accuracy. The procedure is illustrated with selected experimental results for humid air and a silica gel matrix.
Thermosolutal Inducement of No-Slip Free Surfaces in Combined Marangoni-Buoyancy Driven Cavity Flows
Authors: Keller J. R. , Bergman T. L.
Published: May 2008

The presence of a diffusing surfactant in combined surface tension-buoyancy driven convection is studied numerically to examine its influence on the flow structure and heat transfer characteristics of a fluid contained within a cavity. By accounting for the surface tension dependence on both temperature and surfactant concentration, the free surface may become stagnant. As a result, the high local and overall heat transfer rates at the cold wall, which are associated with thermal surface tension-augmented buoyancy driven flows, are decreased.
Unsteady Multicellular Natural Convection in a Narrow Horizontal Cylindrical Annulus
Authors: Fant D. B. , Prusa J. , Rothmayer A. P.
Published: May 2008

Numerical and analytical solutions are presented for multicellular flow instability and the subsequent nonlinear development in a horizontal cylindrical annulus. The Boussinesq approximated Navier–Stokes equations are simplified to Cartesian-like boundary layer equations by means of a high Rayleigh number small gap asymptotic expansion. The full numerical problem is explored for the limiting case of zero Prandtl number. At a finite scaled gap spacing, an instability sets in, which results in periodic multicellular flow. The numerical solutions are found to progress through an increasingly complex sequence of periodic solutions, culminating in a very complex unsteady solution that has features normally associated with chaotic systems.
An Analytical Study on Natural Convection in Isotropic and Anisotropic Porous Channels
Authors: Nilsen T. , Storesletten L.
Published: May 2008

This paper is an analytical study on natural two-dimensional convection in horizontal rectangular channels filled by isotropic and anisotropic porous media. The channel walls, assumed to be impermeable and perfectly heat conducting, are nonuniformly heated to establish a linear temperature distribution in the vertical direction. We derive the critical Rayleigh numbers for the onset of convection and examine the steady flow patterns at moderately supercritical Rayleigh numbers. The stability properties of these flow patterns are examined against two-dimensional perturbations using a weakly nonlinear theory.
A Finite-Volume Method for Predicting a Radiant Heat Transfer in Enclosures With Participating Media
Authors: Raithby G. D. , Chui E. H.
Published: May 2008

A new “finite-volume” method is proposed to predict radiant heat transfer in enclosures with participating media. The method can conceptually be applied with the same nonorthogonal computational grids used to compute fluid flow and convective heat transfer. A fairly general version of the method is derived, and details are illustrated by applying it to several simple benchmark problems. Test results indicate that good accuracy is obtained on coarse computational grids, and that solution errors diminish rapidly as the grid is refined.
Numerical Analysis of Heat and Mass Transfer From Horizontal Cylinders in Downward Flow of Air-Water Mist
Authors: Aihara T. , Fu W.-S. , Suzuki Y.
Published: May 2008

A numerical analysis is made of heat and mass transfer from horizontal circular cylinders in a downward flow of air/water mist of polydisperse droplets, taking into account the far-upstream droplet size distribution and the blockage effect of the gas phase flow. The effects of the droplet size distribution, temperatures, and liquid-to-gas mass flow ratio upon the liquid film thickness and wall shear stress, velocity, and temperature of the air-water interface, two-phase Nusselt numbers, etc., are examined.
The Temperature Distribution Around a Spherical Particle on a Planar Surface
Authors: Fransaer J. , De Graef M. , Roos J.
Published: May 2008

The solutions for three related boundary value problems in tangent sphere coordinates are presented; two of these problems involve a conducting and a nonconducting sphere on a conducting flat surface when the field at infinity is linear. The third problem describes the potential field around a conducting sphere on an insulating surface where the field at infinity vanishes. Depending on the nature of the problem, either the Laplace equation or the Stokes stream function formalism is used. The integral solutions are rewritten as series expansions, which are numerically easier to evaluate.
The Effects of Wall Thermal Resistance on Forced Convection Around Two-Dimensional Bodies
Authors: Luchini P. , Lupo M. , Pozzi A.
Published: May 2008

The influence of wall thermal resistance on stagnation and supersonic wedge flow is studied in this paper. The equation of heat conduction inside the wall is transformed by a suitable approximation into boundary conditions for the equations of heat transfer in the fluid, which are then solved for several situations. The method of solution is based on series expansions, the convergence of which is improved through the Pade´ approximation technique. The results, exact for all purposes in the entire field, are discussed in terms of the interface temperature and Nusselt number.
Steady-State Modeling and Testing of a Micro Heat Pipe
Authors: Babin B. R. , Peterson G. P. , Wu D.
Published: May 2008

A combined experimental and analytical investigation was conducted to identify and understand better the phenomena that govern the performance limitations and operating characteristics of micro heat pipes—heat pipes so small that the mean curvature of the vapor—liquid interface is comparable in magnitude to the reciprocal of the hydraulic radius of the flow channel. The analytical portion of the investigation began with the development of a steady-state model in which the effects of the extremely small characteristic dimensions on the conventional steady-state heat pipe modeling techniques were examined. In the experimental portion of the investigation, two micro heat pipes, one copper and one silver, 1 mm2 in cross-sectional area and 57 mm in length, were evaluated experimentally to determine the accuracy of the steady-state model and to provide verification of the micro heat pipe concept. Tests were conducted in a vacuum environment to eliminate conduction and convection losses. The steady-state experimental results obtained were compared with the analytical model and were found to predict accurately the experimentally determined maximum heat transport capacity for an operating temperature range of 40° C to 60° C. A detailed description of the methodology used in the development of the steady-state model along with a comparison of the predicted and experimental results are presented.
Effect of Entrainment on the Heat Transfer to a Heated Circular Air Jet Impinging on a Flat Surface
Authors: Goldstein R. J. , Sobolik K. A. , Seol W. S.
Published: May 2008

An experimental investigation is described that characterizes the convective heat transfer of a heated circular air jet impinging on a flat surface. The radial distributions of the recovery factor, the effectiveness, and the local heat transfer coefficient are presented. The recovery factor and the effectiveness depend on the spacing from jet exit to the impingement plate, but do not depend on jet Reynolds number. The effectiveness does not depend on the temperature difference between the jet and the ambient. A correlation is obtained for the effectiveness. The heat transfer coefficient is independent of the temperature difference between the jet and the ambient if it is defined with the difference between the heated wall temperature and the adiabatic wall temperature.
Mixed Convection Heat Transfer With Longitudinal Fins in a Horizontal Parallel Plate Channel: Part I—Numerical Results
Authors: Maughan J. R. , Incropera F. P.
Published: May 2008

Numerical calculations for laminar, fully developed mixed convection in a longitudinally finned horizontal channel have been performed for two sets of boundary conditions: (i) an isothermal, heated bottom plate with an isothermal, cooled top plate, and (ii) a uniform heat flux at the bottom surface with an adiabatic upper surface. Heat transfer and the strength of the buoyancy-driven secondary flow increase with increasing Rayleigh number and fin height. Fin spacing affects heat transfer through changes in the axial velocity distribution, the strength of the secondary flow, and the heated surface area, with decreased spacing acting to inhibit secondary flow. For the uniform heat flux condition and a small available pressure drop, close fin spacing can significantly reduce the channel flow rate and increase maximum plate temperatures.
Mixed Convection Heat Transfer With Longitudinal Fins in a Horizontal Parallel Plate Channel: Part II—Experimental Results
Authors: Maughan J. R. , Incropera F. P.
Published: May 2008

Experiments have been performed to investigate the effects of longitudinal fins on laminar mixed convection in airflow between parallel plates, with the bottom plate heated isothermally and the top plate cooled isothermally. In addition to the un-finned condition, nondimensional fin spacings in the range 0.25 < A < 2.0 were considered for relative fin heights of F = 0.5 and 0.9 and for the Rayleigh number range 760 < Ra < 29700. For fully developed flow over the unfinned surface, square longitudinal vortices (A = 1.0) were observed for Ra > Rac and persisted until Ra ≈ 20,000. While data for closely spaced fins showed considerable enhancement at lower Rayleigh numbers due to the additional surface area, the development of vigorous secondary flow was delayed. Hence, for fully developed conditions and F = 0.5, Nusselt numbers for the finned surface were, in some instances, lower than those for mixed convection without fins. Results are compared to previous numerical predictions, and it is shown that agreement is good until the flow violates modeling assumptions of steady, symmetric flow between fins.
Investigation of Natural Convection in Partially Divided Rectangular Enclosures Both With and Without an Opening in the Partition Plate: Measurement Results
Authors: Chen K. S. , Ku A. C. , Chou C. H.
Published: May 2008

Experimental results are presented for steady natural convection in a two-dimensional, partially divided, rectangular enclosure, in which two of the vertical walls were maintained at different uniform temperatures and the top and bottom walls were insulated. The partition plate was adiabatic, and the experiment was carried out both with and without an opening in the partition. Rayleigh numbers ranging from 106 to 108 and opening ratios of 0, 1/8, and 1/4 were investigated for an enclosure aspect ratio (length/height) of 2 and Prandtl number of 7 (for water). Local velocity and temperature measurements were made with a laser-Doppler velocimeter and thermocouple probes. Flow visualization using colored dye was also performed. Results show that there was a recirculation zone in the upper and left quadrant of the enclosure when there was no opening in the partition plate. With an opening in the partition, the recirculation zone was absent and the heat transfer rate increased. An unopened partial obstruction would reduce the heat transfer rate by an amount of 12 to 30 percent depending on the Rayleigh number. However, the opening seems to have little effect on the velocity and temperature profiles of the left-moving fluid on the bottom wall. A correlation of the Nusselt number is derived, which shows that the heat transfer rate increases as the Rayleigh number or opening ratio increases.
Flow Transitions in Buoyancy-Induced Non-Darcy Convection in a Porous Medium Heated From Below
Authors: Kladias N. , Prasad V.
Published: May 2008

Thermoconvective instabilities in horizontal porous layers heated from below are studied numerically by employing the Brinkman-Forchheimer extended Darcy formulation. The onsets of stable and oscillatory convection are found to be strong functions of the governing parameters: fluid Rayleigh and Prandtl numbers, Darcy number, and conductivity ratio. The effects of porosity and specific heat ratio are pronounced only in the fluctuating convection regime. At the onset, the oscillatory convection is highly periodic, but with an increase in convective motions the disorder increases monotonically and the fluctuations become highly random. These results do not confirm the possibility of reverse transition from a more-disordered to a less-disordered state as predicted by the Darcy model (Kimura et al., 1986). The applicability of Darcy formulation is thus highly restricted in the case of a Be´nard convection problem. In a randomly oscillating convective state, the heat transfer rate varies substantially with time.
Scaled Isotropic Results for Two-Dimensional Anisotropic Scattering Media
Authors: Kim T.-K. , Lee H. S.
Published: May 2008

The full anisotropic scattering solutions of the radiative equation of transfer are compared with the scaled isotropic scattering solutions. Square enclosures with a collimated incidence, a diffuse incidence, or an isothermal emission are considered for comparison. The isotropic scaling approximation is found to predict accurately the radiative flux and the average incident radiation for the isothermal emission problem and for most diffuse incidence problems. For the collimated incidence problem, the isotropic scaling solutions are acceptable only for weakly scattering media. For large scattering albedo the error in the isotropic scaling is appreciable for the diffuse incidence problem and unacceptably large for the collimated incidence problem. The largest error in the y-direction net flux is found at the side wall regions when the medium is purely scattering. The isothermal emission problem or problems with symmetric boundary conditions can be accurately modeled by a scaled isotropic phase function, since the effect of the phase function anisotropy is negligible in such problems.