bluuebunny/crossref_metadata_2025 huggingface dataset:
Concurrent analysis of intracellular glutathione content and gap junctional intercellular communication
Authors: Barhoumi Rola , Bowen Jeffery A. , Stein Lisa S. , Echols Jana , Burghardt Robert C.
Published: August 2005

The potential for performing dual analysis of intracellular glutathione levels and assessment of gap junctional intercellular communication with thiol‐specific fluorescent probes in anchored cells was evaluated. Gap junction‐mediated diffusion of monochlorobimane and 5‐chloromethylfluorescein diacetate following intracellular loading and conjugation with glutathione was compared with 5‐carboxyfluorescein diacetate (which is routinely used in laser cytometry to monitor intercellular communication) by means of fluorescence recovery after photobleaching using a variety of communication‐competent and communication‐incompetent cells. The rate of diffusion of fluorescence among communication‐competent cells was inversely proportional to the size of the fluorescent probe employed. The thiol‐specific probes were also employed to monitor depletion and synthesis of glutathione following treatments to inhibit glutathione synthesis or consume glutathione by adduct formation. Analysis of gap junctional intercellular communication following glutathione depletion revealed a direct correlation between glutathione levels and intercellular communication. These studies support the utility of the thiol‐specific probes to monitor the respective role of cellular glutathione and intercellular communication in the mechanisms of cellular injury. © 1993 Wiley‐Liss, Inc.
Nucleated cells response to protein electroinsertion
Authors: Mouneimne Youssef , Brown Wendy C. , Nicolau Claude , Tosi Pierre‐François
Published: August 2005

Application of an electrical pulse field at a strength slightly below the value required for electroporation to a suspension of red blood cells in the presence of membrane xenoproteins leads to the insertion of those proteins in the erythrocyte plasma membrane. This observation is extended to nucleated cells. In the presence of glycophorin A, application of such pulses leads to the insertion of 104–105 molecules of glycophorin A per cell in CEM‐CM3, Hela S3, and bovine CD8+ T cells. Electroinserted glycophorin A is detected by flow cytometry using antiglycophorin monoclonal antibodies. The survival of the cells subjected to electroinsertion was 55% for CEM‐CM3 cells, 69% for Hela S3 cells, and 65% for CD8+ T cells. Cells cultured after electroinsertion lost the electroinserted glycophorin A, with two different rates, by a temperature and cell type‐eependent mechanism. During the first 2 h after electroinsertion, the CD8+ T cells lost 12.5% of the inserted glycophorin A per h, the CEM‐CM3 cells lost 7.7% per h, whereas the Hela S3 cells lost only 0.8% of the inserted protein per h. After 2 h, the rate increased substantially, to 41.7% per h for the CD8+ T cells, 13.5% for the CEM‐MM3 cells, and 8.9% for the Hela S3 cells. Cytochalasin D efficiently inhibited the disappearance of electroinserted glycophorin A during the first 2 h after electroinsertion only. © 1993 Wiley‐Liss, Inc.
Characterization of the differentiation of human colorectal cancer cell lines by means of Voronoi diagrams
Authors: Darro Francis , Kruczynski Anna , Etievant Chantal , Martinez Jean , Pasteels Jean‐Lambert , Kiss Robert
Published: August 2005

This paper describes differentiation in terms of population dynamics through the medium of Voronoi paving which enables (via digital cell image analysis) the structure of human LOVO and HCT‐15 colorectal neoplastic cell colonies growing on histological slides to be characterized. Two other tests were also used, i.e., the colorimetric MTT assay that enables the cell growth level to be determined, and a test allowing the assessment of the proliferation index, i.e., the percentage of cells in the S phase of the cell cycle. The results show that these colorectal neoplastic cells exhibited a comparatively high level of organisation in terms of the topographical distribution of nuclei within the clones when the cells were cultivated in media containing even small amounts of fetal calf serum. On the other hand, certain chemically defined media completely overturned this “pseudo‐tissular” architecture. Furthermore, the colorectal cells growing in media including fetal calf serum exhibited relatively large and dense clones, undergoing an increase in the density of these clones when hormones were added to the culture medium and, concomitantly, a decrease in their proliferation. In contrast, the cells growing in chemically defined media generally exhibited smaller clones whose cell proliferation was paradoxically greater than that of the cells referred to above. This seems to bring out the importance of the part played by the cell loss factor in this cell population dynamic. © 1993 Wiley‐Liss, Inc.
Preferential loss of abnormal prostate carcinoma cells by collagenase treatment
Authors: König Josée J. , van Dongen Jan Willem , Schröder Fritz H.
Published: August 2005

Effects of two different methods of tumor disaggregation on flow cytometric ploidy distribution and intact cell yield were investigated. Either mechanical disaggregation or collagenase digestion was applied to 35 prostate tumor specimens. Seven collagenase‐treated samples failed to yield any intact cells, whereas with mechanical disaggregation in all cases a sufficient number of intact cells were obtained. No differences in the FCM ploidy distribution of tumors with a DNA diploid stemline were observed comparing both techniques. In DNA aneuploid tumors, however, collagenase treatment had an adverse effect on the abnormal cell populations. In 14/17 of such tumors, the abnormal cell populations were significantly reduced; in eight of these the percentage of DNA aneuploid cells declined even below the minimum percentage (10%) that was defined for DNA aneuploidy. Since collagenase is a widely used enzyme for tissue disaggregation, especially in tumor cytogenetics, the presented data will have consequences for the interpretation of results obtained by methods involving the use of this enzyme. © 1993 Wiley‐Liss, Inc.
Rapid flow cytometric antibiotic susceptibility assay for Staphylococcus aureus
Authors: Ordóñez José V. , Wehman Natalie M.
Published: August 2005

Conventional techniques for antibiotic susceptibility testing usually require 24 h or more to produce accurate results. This long waiting period to demonstrate antibiotic action is necessary because such tests rely on growth (or the lack of it), when the microorganisms are incubated in the presence of the antibiotic. In an effort to improve antibiotic susceptibility testing, we developed a flow cytometric technique for Staphylococcus aureus in which antibiotic action is determined by monitoring drug‐gnduced membrane potential changes, using the potential‐sensitive dye 3,3′‐dipentyloxacarbocyanine iodide. Three ATCC reference strains of S. aureus and 13 unknown strains of the same microorganism were tested for susceptibility to penicillin G and oxacillin. Our results indicate that susceptibility of S. aureus to these antibiotics can be measured reliably at 90 min after addition of the antibiotic, and the results are comparable to those obtained with conventional susceptibility tests. © 1993 Wiley‐Liss, Inc.
Beam‐shaping optics for a slit‐scan flow cytometer
Authors: Noguchi Yoshio , Kashima Shingo , Aikata Takashi
Published: August 2005

Two sets of beam‐shaping optical systems for slit‐scan flow cytometry were made for 360 nm and 488 nm wavelength argon‐ion lasers. A thin, ribbonlike laser beam was formed by compressing the zero‐order component of Fraunhofer diffraction patterns caused by a slit vertically long and horizontally narrow by means of an objective with a numerical aperture of 0.5. The objectives were designed to include a jet stream that performed as a cylindrical lens. The characteristic values of the optical systems and lens alignments of the systems are described in this work. The beam size at focus was 0.95 μm in thinness and 85.0 μm in width on design values. The actual beam thinness for the UV laser was estimated to be 1.3 μm, based on shapes of pulses generated when fluorescence microspheres of diameter 1.0 μm passed across the beam. The usefulness of the optical systems was also proved by its ability to measure HeLa chromosomes. © 1993 Wiley‐Liss, Inc.
Flow cytometric assay of pinocytosis: Correlation with membrane ruffling and metastatic potential in the dunning R‐3327 rat prostatic adenocarcinoma model
Authors: Mohler James L. , Sharief Yousuf
Published: August 2005

Membrane ruffling has been associated with neoplastic transformation, Harvey ras expression, and metastatic capability. In the Dunning R‐3327 rat prostatic adenocarcinoma model, membrane ruffling graded visually upon live cultured cells filmed by time‐lapse video‐microscopy has distinguished sublines of high and low metastatic potential. Fluid‐phase pinocytosis is a constitutive, noninducible internalization of medium by cell membrane. Fluid phase pinocytosis may be measured flow cytometrically by cellular uptake of fluorescein‐labelled medium constituents.

The optimum conditions for a flow cytometric assay of pinocytosis were determined using AT‐2 subline that has an intermediate degree of membrane ruffling. The optimum dextran concentration was selected from the midpoint of the linear portion of the dose‐eesponse (0.01–10.00 mg/ml) curve, whereas the optimum incubation time was determined from a time course (1—405 min.) curve study. Cultured cells from 6 Dunning sublines incubated with 1.0 mg/ml of fluorescein‐labelled dextran for 90 min were washed, fixed, and the fluorescence of 10,000 cells studied by flow cytometry. For each subline, dextran fluorescence was measured in four independent experiments. Pinocytosis failed to distinguish sublines of high (AT‐3 63.5 ± standard error 4.1 mean channel number, MAT‐LyLu 63.2 ± 6.3, MAT‐tu 64.3 ± 5.6) and low (G 33.5 ± 1.2, AT‐1 63.5 ± 4.1, AT‐2 58.4 ± 3.6) (rank p = 0.38) metastatic potential but correlated strongly with visually graded membrane ruffling (r = 0.95, p = 0.003). Pinocytosis assayed by flow cytometry reflects membrane ruffling observed visually and thus flow cytometric assays may facilitate study of membrane activity. © 1993 Wiley‐Liss, Inc.
Development of a shape vector that identifies critical forms assumed by human polymorphonuclear neutrophils during chemotaxis
Authors: Hartman Raymond S. , Lau Kin , Chou William , Coates Thomas D.
Published: August 2005

Human polymorphonuclear neutrophils undergo characteristic shape changes that are critical to their ability to move and ingest their targets. We present here the construction of a simple shape vector, calculated from the coordinates of the cell perimeter, that can identify critical forms that a neutrophil assumes during the course of ameboid movement. The vector can be used to find neutrophils of a specific shape from the image analyzer data produced during a typical neutrophil tracking experiment. © 1993 Wiley‐Liss, Inc.
Quantitation of adhesion molecules and other function‐associated antigens on human peripheral blood leucocytes
Authors: Macey M. G. , McCarthy D. A.
Published: August 2005

Quantitating satisfactorily the expression of adhesion molecules and other functional antigens on the surface of human peripheral blood granulocytes by flow cytometry is difficult. Artefactual (in vitro) changes, which occur in the expression of these molecules during conventional cell preparation and labelling procedures, led to the development of a leucocyte preparation technique that prevents upregulation of the leucocyte integrins and other antigens. The technique, as originally evaluated, involves fixing freshly drawn blood with formaldehyde (final concentration 0.2%) for 4 min at 37°C before adding ammonium chloride to lyse the erythrocytes; procedures which are inconvenient when blood samples are taken in wards or clinics that are some distance from a laboratory. We therefore investigated (i) whether blood could be kept with commonly used anticoagulants for up to 1 h before fixation, and (ii) whether unantico agulated blood could be kept with formaldehyde for a similar period before processing was continued. The results showed that when quantitating those granulocyte surface antigens which can be rapidly upregulated: (i) that it is preferable to mix freshly drawn unanticoagulated blood directly with formaldehyde; (ii) that if blood must be collected into anticoagulants, it should be kept for only the briefest possible time before processing; and (iii) that the time for which cells are exposed to 0.2% formaldehyde must be carefully controlled and limited to 4 min. A corollary of the results with anticoagulants is that it is probably impossible to isolate live granulocytes by currently available procedures without artefactually altering the expression of these antigens in vitro. © 1993 Wiley‐Liss, Inc.
Differences in relative DNA content between human peripheral blood and bone marrow subpopulations–consequences for DNA index calculations
Authors: Jensen Inger Marie , Ellegaard Jørgen , Hokland Peter
Published: August 2005

By sequentially staining for leukocyte differentiation antigens with monoclonal antibodies and for stainable DNA content with propidium iodide, we have evaluated the DNA ratios of normal peripheral blood and bone marrow subpopulations. In 19 peripheral blood samples the relative DNA content of the monocytes was higher than that of other subpopulations, with highly significant differences between the DNA ratios of the CD14+ monocytes, on the one hand, unlabeled controls, CD3+ T‐lymphocytes, and CD20+ B‐lymphocytes, on the other. In bone marrows from 16 healthy volunteers, the relative DNA content of the myelomonocytic subpopulations was higher than that of the T‐lymphocytes with significant differences between the CD3+ lymphocytes, on the one hand, and the CD14+ monocytes, the CD13+ and CD33+ immature myeloid, the NAT9+ mature myeloid, and the AS‐E1+ nucleated erythroid subpopulation, on the other. Since a mixture of peripheral blood mononuclear cells or T lymphocytes from healthy volunteers is often used as an external standard for DNA ploidy determinations, these data suggest that such a procedure could result in an overestimation of the DNA indices of most of the bone marrow subpopulations. Instead, we suggest the use of the DNA ratio of the CD14+ subpopulation from peripheral blood as standards for ploidy determinations for the myeloid bone marrow subpopulations. © 1993 Wiley‐Liss, Inc.
Flow and image cytometry for DNA analysis in bladder washings: Improved concordance by using internal reference for flow
Authors: Chabanas Agnègs , Rambeaud Jean‐Jacques , Seigneurin Daniel , Fradet Yves , Lawrence Jean‐Jacques , Faure Gilbert
Published: August 2005

Using flow or image cytometry, we compared the DNA distribution of cells from bladder washings from 52 patients with bladder cancer. For image cytometry, urothelial nuclei (recognized visually) were analyzed for DNA content using polymorphonuclear nuclei as internal diploid reference. For flow cytometry, two methods can be used: either all cells can be analyzed, as commonly performed, or urothelial cells can be analyzed alone, after specific derection. In this flow cytometry study, cells were doubly stained for panurothelial antigen T16 and for DNA. All the cells were first analyzed using peripheral lymphocytes as an external reference; 79% of the results were similar with results obtained from image analysis. For discordant results, flow‐cytometric data were reprocessed to identify immunologically stained urothelial cells; one additional case became concordant with image cytometry when only urothelial cells were analyzed, with lymphocytes as diploid reference; a better concordance (94%) was found when the nonurothelial cells of the samples served as a diploid reference instead of peripheral lymphocytes. This suggests that we achieved an improvement of the flow‐cytometric evaluations for ploidy assessement, and we conclude that, on these conditions, flow or image analysis can be considered as equivalent methods for DNA content studies of tumors. © 1993 Wiley‐Liss, Inc.
Subtraction of autofluorescent dead cells from the lymphocyte flow cytometric binding assay
Authors: Zamai L. , Bareggi R. , Santavenere E. , Vitale M.
Published: August 2005

Flow cytometry allows the quantitative analysis of lymphocyte–target cell conjugates and the identification of the lymphocyte subset involved in the binding phenomenon. We recently described a methodology to identify the effector cells bound to K562 targets based on target cell autofluorescence coupled with lymphocyte staining by means of fluorescent monoclonal antibodies. Here we describe an implementation of the methodology that allows the subtraction of spontaneously dead targets to which lymphocytes may or may not adhere, thereby preventing the overestimation of the binding phenomenon and limiting its evaluation to living effector‐target conjugates, thus preserving the specificity of the phenomenon. © 1993 Wiley‐Liss, Inc.
Rapid separation of CD4+ and CD19+ lymphocyte populations from human peripheral blood by a magnetic activated cell sorter (MACS)
Authors: Semple John W. , Allen David , Chang Wilda , Castaldi Patrick , Freedman John
Published: August 2005

Rapid purification of human lymphocyte subpopulations is an essential step in order to elucidate their interactions and/or contributions in various disease states. Cell purification using a Magnetic Activated Cell Sorter (MACS) is a relatively new technology which has been shown to be rapid and yield highly purified populations of cells. This report describes both a simple one‐step positive selection method using the MACS to purify either human CD4+ or CD19+ lymphocytes from PBMC and a sequential separation of both CD4+ and CD19+ cell populations. These methods can separate the cell populations in approximately 4 h with yields >90% and purity of 97 ± 3% for CD4+ T cells and 92 ± 5% for CD19+ B cells. In functional studies, purified CD19+ B cells secreted 13‐ and 24‐fold more IgM and IgG, respectively, than the CD19− cell fraction in 10 day B cell stimulation assays. Purification of the two cell types did not cause any significant activation as shown by proliferation. Both cell types, however, were able to proliferate upon stimulation with interleukin‐2. © 1993 Wiley‐Liss, Inc.
Synthesis, Absorption, and Fluorescence‐Emission Properties of 1,3,6,8‐Tetraethynylpyrene and Its Derivatives
Authors: Venkataramana Gandikota , Sankararaman Sethuraman
Published: August 2005

The synthesis of several 1,3,6,8‐tetraethynylpyrene derivatives is reported. The effect of extended acetylenic conjugation on their absorption and fluorescence‐emission properties is studied. Significant bathochromic shifts of both the absorption and fluorescence emission bands are observed. These derivatives emit fluorescence in the visible (400–550 nm) region. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Cyclooctyne and 4‐Cyclooctyn‐1‐ol – Versatile Building Blocks in Organic Synthesis
Authors: Heber Dieter , Rösner Peter , Tochtermann Werner
Published: August 2005

The readily available and highly reactive title compounds represent versatile building blocks in organic synthesis. Recent examples of 1,3‐dipolar cycloadditions and Diels–Alder reactions and their applications are described. This microreview is especially devoted to cycloadducts formed between1and2and furans, and their transformations to give a variety of different classes of compounds, including derivatives of natural products. Here the conversion of oxanorbornadienes into bridged oxepines plays an important role in many cases. Different routes to enantiomerically pure compounds are also presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Simplified stripping potentiometry methodology: Application to the determination of lead in wine
Authors: Jagner Daniel , Renman Lars , Wang Yudong
Published: August 2005

Wine samples (120 μL) were pipetted into a 480 μL matrix modifying solution in a disposable Eppendorff tube. The modifying solution was comprised of hydrochloric acid, Hg(II), Ca(II), Al(III), Mn(II), 10% v/v Triton X‐100, 25% v/v EtOH, and Bi(III) as an internal standard. The mixture was transferred to a novel sample rotation assembly, used in combination with a cylindrical combined glassy carbon working electrode and Ag/AgCl reference and counter electrodes, and analyzed for 3 minutes by means of stripping potentiometry (SP). The analytical procedure, including control of all instrumental parameters and evaluation of the results, was performed fully automated using a commercial stripping analyzer and accompanying software. Calibration was performed using two aqueous standards, and due to the use of the internal standard, the same calibration curve could be used indefinitely. The relative precision was estimated to 5% and the detection limit to 3 μ/L. Good agreement was obtained between the results obtained by the proposed method and those obtained by isotope dilution inductively coupled plasma‐mass spectrometry (ICP‐MS) in the analysis of four red and four white wine samples, ranging in lead concentration from 18 to 151 μg/L, with the maximum relative difference between the two techniques being 11.5%.
Oxidative behavior of the sulfonamidic diuretic bumetanide at carbon paste electrode
Authors: Legorburu María J. , Alonso Rosa M. , Jiménez Rosa M.
Published: August 2005

The oxidative behavior of the 3‐(aminosulfonyl)‐5‐(butylamino)‐4‐phenoxy‐benzoic acid, Bumetanide, was studied in hydroalcoholic media (9:91 MeOH:H2O, pH range 1–9) and in two different ionic media (KNO3 and KCl) at a carbon paste electrode. The oxidation process has been shown to be irreversible and predominantly diffusion‐controlled over the entire pH range and in both media. A voltammetric method was developed at pH = 2.5 (phosphate buffer) and 0.4 M KNO3 for the quantitative determination of Bumetanide. The peak current was linear with the Bumetanide concentration in the range 2.74 × 10−6 M‐2.74 × 10−5 M with a detection limit of 4.39 × 10−7 M (0.16 ppm) and a reproducibility (in terms of relative standard deviation) of 3.61 and 7.60% for 10 determinations of 1.25 × 10−5 M and 4.99 × 10−6 M concentrations, respectively. The method for Bumetanide was applied to assays of pharmaceuticals (Fordiuran, 1 mg) and urine.
Improved finite element forms for the shallow‐water wave equations
Authors: Williams R. T. , Zienkiewicz O. C.
Published: August 2005

This paper presents new finite element formulations of the shallow‐water wave equations which use different basis functions for the velocity and height fields. These arrangements are analysed with the Fourier transform technique which was developed by Schoenstadt,1 and they are also compared with other finite difference and finite element schemes. The new schemes are integrated in time for two initial states and compared with analytic solutions and numerical solutions from other schemes. The behaviour of the new forms is excellent and they are also convenient to apply in two dimensions with triangular elements.
Numerical solutions of Navier‐Stokes equations with an integrated compartment method (ICM)
Authors: Yeh Gour‐Tsyh
Published: August 2005

The most common numerical methods that are used by physical scientists to approximate partial differential equations employ finite differences and/or finite elements. In addition, compartment analyses have been adopted by ecological system analysts to simulate the evolution of processes governed by differential equations without spatial derivatives. An integrated compartment method (ICM) is proposed to combine the merits of these three numerical techniques. The basic procedures of the ICM are first to discretize the region of interest into compartments, then to apply three integral theorems of vectors to transform the volume integral to the surface integral, and finally to use interpolation to relate the interfacial values in terms of compartment values to close the system. These procedures are applied to the Navier‐Stokes equations to yield the computational algorithm from which computer programs can be coded. The computer code is designed to solve one‐, two‐, or three‐dimensional problems as desired. The program is applied to two simple cases: wake formation behind an obstacle in a channel and circulatory motion of a body of fluid in the square cavity. These preliminary applications have shown promising results.
Applicability of algebraic models based on unidirectional flow to duct flow with lateral motion
Authors: Naot D. , Rodi W.
Published: August 2005

The solution for the stress transport turbulence model equations for the situation where the flow is unidirectional is now commonly applied to flows with weak secondary currents in closed ducts, open channels, and rod bundles in nuclear reactor channels. Here, perturbations to the unidirectional flow solutions are studied by solving the exact equations using an iterative procedure. Now the equations also contain the small lateral velocity gradients formerly neglected. The applicability as well as the limitation of the use of the unidirectional flow turbulence model for the description of channel flow with lateral motion are discussed. Modifications for weak lateral motion are suggested.
Numerical calculation of transitional boundary layers
Authors: Arad E. , Berger M. , Israeli M. , Wolfshtein M.
Published: August 2005

A computational procedure for compressible axisymmetric boundary layers, on bodies of revolution, in transition from laminar to turbulent flow, is introduced. The procedure is an extension of a former method, due to Patankar and Spalding.

The flow field is computed by solution of four simultaneous equations for the momentum, the thermal energy, the turbulence energy amplitude and the turbulent scale.

The results show good agreement with existing theoretical and experimental data.
Consistent vs. reduced integration penalty methods for incompressible media using several old and new elements
Authors: Engelman M. S. , Sani R. L. , Gresho P. M. , Bercovier M.
Published: August 2005

The frequently used reduced integration method for solving incompressible flow problems ‘a la penalty’ is critically examined vis‐a‐vis the consistent penalty method. For the limited number of quadrilateral and hexahedral elements studied, it is shown that the former method is only equivalent to the latter in certain special cases. In the general case, the consistent penalty method is shown to be more accurate. Finally, we demonstrate significant advantages of a new element, employing biquadratic (2‐D) or triquadratic (3‐D) velocity and linear pressure over that using the same velocity but employing bilinear (2‐D) or trilinear (3‐D) pressure approximation.
Numerical solution of free surface, porous flow problems
Authors: Casulli V. , Greenspan D.
Published: August 2005

An inexpensive, finite difference numerical method is developed for the approximate solution of general, free surface, porous flow problems. The method is so designed that the required numerical boundary conditions coincide exactly with the required physical boundary conditions. In the present paper, application is made to prototype, steady state, dam flow problems.
Utilization of the method of characteristics to solve accurately two‐dimensional transport problems by finite elements
Authors: Varoḡlu Erol , Finn W. D. Liam
Published: August 2005

A new finite element method is presented for the solution of two‐dimensional transport problems. The method is based on a weighted residual formulation in which the method of characteristics is combined with the finite element method. This is achieved by orienting sides of the space‐time elements joining the nodes at subsequent time levels along the characteristics of the pure advection equation associated with the transport problem. The method is capable of solving numerically the advection‐‐diffusion equation without generating oscillations or numerical diffusion for the whole spectrum of dispersion from diffusion only through mixed dispersion to pure convection.

The utility and accuracy of the method are demonstrated by a number of examples in two space dimensions and a comparison of the numerical results with the exact solution is presented in one case. A very favourable feature of the method is the capability of solving accurately advection dominated transport problems with very large time steps for which the Courant number is well over one.
Analysis of two‐dimensional, finite amplitude wave propagation by time marching methods
Authors: Parker R. , James M. N.
Published: August 2005

Two‐dimensional, finite‐amplitude wave propagation in an inviscid, subsonic, perfect gas medium is analysed by explicit finite‐difference methods. A two‐step, Lax‐Wendroff method and the single‐step, Lax‐Friedrichs method are used. A prescribed propagating velocity or pressure disturbance is applied along a single row of grid points normal to the stream direction and results in a 'forced' outflow boundary. The inflow boundary is placed far from outflow by utilizing a streamwise expanding grid and uniform inflow is imposed. Side boundaries are spatially periodic. The numerical solutions are compared with analytical small‐perturbation solutions; higher‐order effects arising from non‐linearities are revealed by Fourier analysis. Solutions which closely approached a periodic state were obtained. The Lax‐Wendroff method combined with the expanding grid is shown to be accurate and stable, the Lax‐Friedrichs scheme produced highly damped solutions.
Numerical solution of a first‐order conservation equation by a least square method
Authors: Chattot J. J. , Guiu‐Roux J. , Lamine J.
Published: August 2005

Least square methods have been frequently used to solve fluid mechanics problems. Their specific usefulness is emphasized for the solution of a first‐order conservation equation. On the one hand, the least square formulation embeds the first‐order problem into equivalent second‐order problem, better adapted to discretization techniques due to symmetry and positive‐definiteness of the associated matrix. On the other hand, the introduction of a least square functional is convenient for finite element applications.

This approach is applied to the model problem of the conservation of mass (the unknown is the density ρ) in a nozzle with a specified velocity field (u, v), possibly including jumps along lines simulating shock waves. This represent a preliminary study towards the solution of the steady Euler equations.

A finite difference and a finite element method are presented. The choice of the finite difference scheme and of a continuous finite element representation for the groups of variables (ρu, ρv) is discussed in terms of conservation of mass flux. Results obtained with both methods are compared in two numerical tests with the same mesh system.
A transonic quasi‐3D analysis for gas turbine engines including split‐flow capability for turbofans
Authors: Habashi W. G. , Youngson G. G.
Published: August 2005

A numerical approximation is taken to the solution of the complex flows existing in gas turbine engines with transonic blading. The quasi‐3D approach decouples the problem into through‐flow and blade‐to‐blade solutions. An industrially practical finite element through‐flow solution is developed and for blade‐to‐blade solutions a transonic finite areas method is utilized. The finite element code developed is capable of operating in an analysis or a design mode. In both modes a dynamic relaxation factor is employed and considerable reduction in solution time can be achieved. Comparisons to streamline curvature methods are carried out for simple analytical and complex industrial problems.
Optimal numerical method for simulating dynamic flow of gas in pipelines
Authors: Osiadacz A.
Published: August 2005

Finite difference methods for solving the linear model describing unsteady state flow in pipelines are considered in the present paper. These methods are compared with each other in order to determine the best one, which meets the criteria of accuracy and relatively small computation time.
A finite element method for high Reynolds number viscous fluid flow using two step explicit scheme
Authors: Kawahara Mutsuto , Hirano Hirokazu
Published: August 2005

This paper presents the finite element method for the analysis of unsteady viscous flow of fluid at high Reynolds numbers. The method is based on the explicit numerical integration scheme in time and uses three node triangular finite elements. For the convenience of the formulation, slight compressibility is considered. For the explicit scheme, the selective lumping two step scheme has been successfully employed. Vortex shedding behind a cylinder has been computed and compared with the conventional experimental results. The results agree favourably when both schemes are compared.
The solution of a convection–diffusion–reaction equation arising from cathodic reduction in a pulsating crack
Authors: Warren M. D.
Published: August 2005

This paper derives the convection–diffusion‐reaction equation governing the reaction between the dissolved oxygen in sea‐water and the steel walls of a pulsating crack. By the neglect of the diffusion term it is shown that an exact solution of the convection‐reaction equation can be obtained. A numerical method for the solution of the complete convection–diffusion‐reaction equation is derived by the use of finite differences. The numerical computation of the initial transient and the final periodic steady‐state values is also discussed.
Natural convection in a square cavity: A comparison exercise
Authors: De Vahl Davis G. , Jones I. P.
Published: August 2005

A number of contributed solutions to the problem of laminar natural convection in a square cavity have been compared with what is regarded as a solution of high accuracy. The purposes of this exercise have been to confirm the accuracy of the bench mark solution and to provide a basis for the assessment of the various methods and computer codes used to obtain the contributed solutions.
OPtimum design for potential flows
Authors: Angrand F.
Published: August 2005

Described in this paper is a methodology for solving a particular class of optimum design problems in Fluid Mechanics, namely optimum design problems for aerofoils when the corresponding fluid flow is potential. The methods described in this paper operate directly in the physical space, and take advantage of the variational formulation of the partial differential equation modelling the flow. The techniques of optimal control, optimization and the finite element method are used. Numerical examples are also given.
A brief note on upwind collocation
Authors: Dougherty D. E. , Pinder G. F.
Published: August 2005

Upwind collocation on Hermite cubics is compared to orthogonal collocation with respect to effective diffusion. The one‐dimensional constant coefficient advection‐diffusion equation is employed to this end. The effective diffusion coefficient is determined exactly and is found to be dependent on the nodal solution values. The effective diffusion coefficients of three other upwinding schemes are also presented. Upwind collocation is found to have an effective diffusion coefficient like other upwinding schemes plus an extra term which may enhance or reduce the non‐advective flux, depending on the problem solution and point location within the domain.
The effect of the choice of the reference pressure location in numerical modelling of incompressible flow
Authors: Jackson C. P.
Published: August 2005

The discontinuity of a finite‐element pressure field that is sometimes present in the neighbourhood of the pressure‐specification‐point is shown to arise either from round‐off, or from mistakes in modelling. The implications of this are considered. In particular it restricts grid refinement near the pressure‐specification‐point. The analysis can be extended to finite‐difference calculations, and to other fields governed by equations similar to Poisson's equation.
Boundary integral equation method for some Stokes problems
Authors: Tözeren Hüsnü
Published: August 2005

The boundary integral equation method is a numerical technique extensively applied in the solution of boundary value problems from many different engineering fields. The starting point of the method is the formulation of an integral equation which gives the variable at any point in terms of single and double layer potentials whose densities are the values of the variable and its derivatives on the boundary. The method consists of the numerical solution of this integral equation when the field point is taken to lie on the boundary. The present paper extends the formulation of the method to Stokes flows of a collection of particles in infinite circular cylinders. This is achieved by developing matrix Green's functions for Stokes flows in cylindrical boundaries. The results are found to be in good agreement with the results of Wang and Skalak1 and Tözeren.3
Finite element simulation of dip coating, II: Non‐Newtonian fluids
Authors: Tanguy P. , Fortin M. , Choplin L.
Published: August 2005

We apply in this paper the augmented Lagrangian method to the study of various non‐Newtonian fluid flow problems, and in particular the dip coating process. We only present in this second part the treatment specific to the non‐linearities involved in the constitutive equations, the first part having largely been concerned with the general description of the approximation used.

Two rheological models illustrating different rheological behaviours are used to simulate dip coating process: the Carreau‐A model for shear‐thinning properties of the viscosity and a truncated second‐order model for a Newtonian behaviour in viscosity with elastic properties.

Numerical predictions show a very good agreement with experimental data for the second‐order model. The discrepancy observed in the other case can be explained qualitatively by the elastic properties exhibited by the shear‐thinning fluids used: this elasticity is not taken into account in the Carreau‐A model.
On some optimization procedures for shock localization
Authors: Vorozhtsov E. V. , Yanenko N. N.
Published: August 2005

We consider a problem on shock wave localization in the numerical solution of one‐dimensional unsteady problems of gas dynamics in Eulerian variables obtained on the basis of finite difference shock‐capturing schemes. An optimization method for strong discontinuity localization proposed previously by Miranker and Pironneau is investigated by means of methods of classical variational calculus. This method may be difficult to implement when the entropy condition is included in the formulation of Miranker and Pironneau's optimization problem as an active constraint. In this connection we suggest an alternative optimization problem using artificial viscosity in the variational principle. It is shown theoretically that the application of such a variational principle yields a trajectory which coincides with the true discontinuity trajectory in the case of a shock wave moving at a constant speed. On the basis of this modification one more algorithm is proposed which reduces the shock localization problem to a problem of minimization of a univariate function. Numerical tests corroborate completely the theoretical conclusions. In particular, a higher shock localization accuracy is obtained on the basis of the proposed algorithms as compared to the original Miranker‐Pironneau method.
The effectiveness of dampers for the analysis of exterior scalar wave diffraction by cylinders and ellipsoids
Authors: Bando K. , Bettess P. , Emson C.
Published: August 2005

The technique of dampers is now widely used in the numerical analysis of unbounded problems. The dampers are used to absorb the outgoing waves. This paper will consider in detail the best formulations of damper methods. Examples will be given showing the effectiveness of three different dampers, in two dimensional and three dimensional models. The geometries considered are circular and elliptical cylinders, spheres and ellipsoids. The results indicate that dampers are indeed very effective, particularly those of higher order, which have recently been developed by Bayliss et al.1,2 and others.
Development of a computer program for the prediction of flow in a rotating cavity
Authors: Chew J. W.
Published: August 2005

A computer program has been developed to predict laminar source‐sink flow in a rotating cylindrical cavity. Although the program is based on a standard finite difference technique for recirculating flow, it incorporates two novel features. Step changes in grid size are employed to obtain sufficient resolution in the boundary layers and special treatment is given to the solution of the pressure correction equations, in the ‘SIMPLE’ algorithm, in order to improve the convergence properties of the method. Results are presented both for the flow in an infinite rotating cylindrical annulus and a finite rotating cylindrical cavity, with the inner cylindrical surface acting as a uniform source and the outer cylinder as a sink. These show good agreement with existing analytical solutions and illustrate some of the problems associated with the computation of rapidly rotating flows.
The solution of non‐linear hyperbolic equation systems by the finite element method
Authors: Löhner R. , Morgan K. , Zienkiewicz O. C.
Published: August 2005

The difficulties experienced in the treatment of hyperbolic systems of equations by the finite element method (or other) spatial discretization procedures are well known. In this paper a temporal discretization precedes the spatial one which in principle is considered along the characteristics to achieve a self adjoint form. By a suitable expansion, the original co‐ordinates are preserved and combined with the use of a standard Galerkin process to achieve an accurate discretization. It is shown that the process is equivalent to the Taylor‐Galerkin methods of Donea.17

Several examples illustrate the accuracy and efficiency attainable in such problems as transport, shallow water equations, transonic flow etc.
The cell Reynolds number myth
Authors: Thompson H. Doyle , Webb Brent W. , Hoffman Joe D.
Published: August 2005

The commonly accepted linear stability analysis for the forward‐time centred‐space (FTCS) algorithm applied to the transport equation has led to the concept of a cell Reynolds number restriction on the spatial grid size. This paper shows where the commonly accepted original analysis is in error and presents the correct stability restrictions, which are restrictions on the time step, not the spatial grid size. There is no cell Reynolds number restriction. The results are confirmed by numerical computations for the two‐dimensional driven cavity problem.
A compatible mixed design and analysis finite element method for the design of turbomachinery blades
Authors: Cedar R. D. , Stow P.
Published: August 2005

In this paper the development of a compatible mixed design and analysis method is presented for the quasi‐three‐dimensional finite element blade‐to‐blade program FINSUP. The method consists of two parts. The first is concerned with a method of modelling changes to a blade shape using a surface transpiration model. The second is concerned with determining the relationship between the displaced blade surface and the surface velocity distribution. It is shown that with the Newton‐Raphson procedure adopted in the method a very efficient manner of introducing the design option is possible. As a consequence the resulting program is fast and completely interactive. A number of examples are given to illustrate how the mixed design and analysis mode can be used in practical blade design.
Numerical outflow boundary conditions for the shallow‐water equations
Authors: Vreugdenhil C. B. , Booij N.
Published: August 2005

A simple explanation is given of the occurrence of wiggles in the flow field near outflow boundaries. If the shallow‐water equations are solved numerically spurious solutions with an oscillatory character turn out to exist, which can be generated by certain additional numerical boundary conditions on the downstream side. The wiggles usually damp quickly with the distance from the boundary. Some ways of handling the downstream boundary are given which largely avoid the occurrence of wiggles.
Mesh effects on the computation of small amplitude water waves
Authors: Toro E. F. , O'Carroll M. J.
Published: August 2005

Computational difficulties arise in the non‐linear free‐surface problem for water waves both at large amplitudes when the crest becomes nearly singular and at small amplitudes when the wave is very close to the alternative uniform flow solution. Since the limiting wavelengths for small amplitude waves are known from the Stokes linearized theory, these are used in checking results for finite‐amplitude programs. When Southwell and Vaisey1 first tried this, their methods gave an unexplained overestimate, by 6 per cent, of the limiting wavelength. This paper shows how coarse mesh effects can create such an overestimate, gives very accurate solutions at small amplitudes and considers accuracy in relation to the mesh for short and long waves.
Analytic test cases for three‐dimensional hydrodynamic models
Authors: Lynch Daniel R. , Officer Charles B.
Published: August 2005

Exact periodic solutions are generated for the 3‐D hydrodynamic equations in linearized form. A linear slip condition is enforced at the bottom, based on the velocity at the bottom. It is shown that the bottom stress can be equivalently expressed in terms of the vertically averaged velocity, and expressions for this bottom stress coefficient are derived in terms of the primary parameters of the problem. As a result, the three‐dimensional structure may be assembled from conventional solutions to (a) the 1‐D vertical diffusion equation; and (b) the 2‐D vertically averaged shallow water equations. In the latter, the bottom stress effects are shown to be complex and frequency‐dependent, and an additional rotational term is required for their representation.
On the performance of quadrilateral finite elements in the solution to the Stokes equations in periodic structures
Authors: Sáez A. E. , Carbonell R. G.
Published: August 2005

The use of the finite element method in solving the problem of flow of a Newtonian fluid in periodically constricted tubes is explored. The performance of eight node serendipity and nine node Lagrangian elements is compared. It was found that the Lagrangian element results in unstable velocity fields when stagnant or recirculation regions are present. This is characteristic of tubes with large expansion zones. The eight node element does not exhibit instabilities. Both elements give accurate pressure fields. This behaviour is contrary to traditional results obtained for flow problems with similar geometrical characteristics. This suggests that the periodicity of the boundary conditions might be the cause of the instabilities in the numerical solution.

The use of the continuity equation to simplify the viscous terms in the Stokes equations resulted, in this particular case, in a deterioration of the rate of convergence of the algorithm.
Solution of the incompressible mass and momentum equations by application of a coupled equation line solver
Authors: Galpin P. F. , Van Doormaal J. P. , Raithby G. D.
Published: August 2005

This paper describes an iterative technique for solving the coupled algebraic equations for mass and momentum conservation for an incompressible fluid flow. The technique is based on the simultaneous solution for pressure and velocity along lines. In a manner similar to ADI methods for a single variable, the solution domain is entirely swept line‐by‐line in each co‐ordinate direction successively until a converged solution is obtained. The tight coupling between the equations that is guaranteed by the method results in an economical solution of the equation set.