bluuebunny/crossref_metadata_2025_split huggingface dataset:
Benchmark solutions for the incompressible Navier–Stokes equations in general co‐ordinates on staggered grids
Authors: Oosterlee C. W. , Wesseling P. , Segal A. , Brakkee E. 
Published: November 2005

AbstractBenchmark problems are solved with the steady incompressible Navier–Stokes equations discretized with a finite volume method in general curvilinear co‐ordinates on a staggered grid. The problems solved are skewed driven cavity problems, recently proposed as non‐orthogonal grid benchmark problems. The system of discretized equations is solved efficiently with a non‐linear multigrid algorithm, in which a robust line smoother is implemented. Furthermore, another benchmark problem is introduced and solved in which a 90° change in grid line direction occurs.
Numerical simulation of a low‐Reynolds‐number turbulent wake behind a flat plate
Authors: Voke Peter R. , Potamitis Socrates G. 
Published: November 2005

AbstractA numerical simulation of a plane turbulent wake at a very low Reynolds number has been performed using finite volume methods. The wake was produced by allowing two turbulent boundary layers, simulated separately in advance, to interact downstream of the trailing edge of a thin flat plate. A number of innovative numerical techniques were required in the simulation, such as the provision of fully turbulent time‐dependent inflow data from a separate simulation, advective outflow boundary conditions and the approximate representation of an internal solid surface by a method which is computationally efficient. The resulting simulation successfully reproduced many of the statistical properties of the turbulent near‐wake flow at low Reynolds number.
Entrance flow in eccentric annular ducts
Authors: Velusamy K. , Garg Vijay K. 
Published: November 2005

AbstractA control‐volume‐based solution of the complete set of Navier‐Stokes equations for the laminar, three‐dimensional developing flow in straight, eccentric, cylindrical annular ducts is described. Numerical results for velocity and pressure development, pressure defect and entrance lengths are presented for a wide range of duct parameters, i.e. relative eccentricity ϵ and radius ratio γ. The present results match very well with earlier numerical solutions for the limiting cases of developing flow in concentric ducts and fully developed flow in eccentric ducts. Comparison with earlier approximate results for developing flow in eccentric ducts indicates that the approximate model predicts the velocity and pressure development with an error of about 10%. However, the development length predicted by the approximate model is grossly in error. The pressure defect and development length in eccentric ducts are very high compared with their counterparts in concentric ducts. The pressure defect, development length and maximum velocity increase with the radius ratio for eccentric ducts, while the reverse is true for concentric ducts. Also, the apparent friction factor decreases as the eccentricity increases.
A little more on stabilized Q1Q1 for transient viscous incompressible flow
Authors: Gresho P. M. , Chan S. T. , Christon M. A. , Hindmarsh A. C. 
Published: November 2005

AbstractIn an attempt to overcome some of the well‐known ‘problems’ with the Q1P0 element, we have devised two ‘stabilized’ versions of the Q1Q1 element, one based on a semi‐implicit approximate projection method and the other based on a simple forward Euler technique. While neither one conserves mass in the most desirable manner, both generate a velocity field that is usually ‘close enough’ to divergence‐free. After attempting to analyse the two algorithms, each of which includes some ad hoc ‘enhancements’, we present some numerical results to show that they both seem to work well enough. Finally, we point out that any projection method that uses a ‘pressure correction’ approach is inherently limited to time‐accurate simulations and, even if treated fully implicitly, is inappropriate for seeking steady states via large time steps.
Parallel finite element simulation of 3D incompressible flows: Fluid‐structure interactions
Authors: Mittal S. , Tezduyar T. E. 
Published: November 2005

AbstractMassively parallel finite element computations of 3D, unsteady incompressible flows, including those involving fluid‐structure interactions, are presented. The computation with time‐varying spatial domains are based on the deforming spatial domain/stabilized space‐time (DSD/SST) finite element formulation. The capability to solve 3D problems involving fluid‐structure interactions is demonstrated by investigating the dynamics of a flexible cantilevered pipe conveying fluid. Computations of flow past a stationary rectangular wing at Reynolds number 1000, 2500 and 107 reveal interesting flow patterns. In these computations, at each time step approximately 3 × 106 non‐linear equations are solved to update the flow field. Also, preliminary results are presented for flow past a wing in flapping motion. In this case a specially designed mesh moving scheme is employed to eliminate the need for remeshing. All these computations are carried out on the Army High Performance Computing Research Center supercomputers CM‐200 and CM‐5, with major speed‐ups compared with traditional supercomputers. The coupled equation systems arising from the finite element discretizations of these large‐scale problems are solved iteratively with diagonal preconditioners. In some cases, to reduce the memory requirements even further, these iterations are carried out with a matrix‐free strategy. The finite element formulations and their parallel implementations assume unstructured meshes.
Transient analysis by Laplace transform and combined finite and boundary element methods for convective diffusion problem
Authors: Okamoto Naotaka , Sawami Hideo 
Published: November 2005

AbstractA numerical method for solving the problem of transient convective diffusion with a first‐order chemical reaction is presented in this paper. The method is applicable over an infinite region. For steady problems the combined method of finite and boundary elements is recognized as a successful numerical technique for dealing with an infinite region. The present method is also useful in transient problems. In order to formulate the combined method for transient problems, we have developed a new method. In this paper the Laplace transform method incorporating the combined finite and boundary element methods will be considered. This transformation, holding complex values, transforms the transient problem into a steady state form. We also consider the present numerical solution which is obtained by using the numerical inverse Laplace transform as presented by Hosono. In numerical experiments the present method gives us an extremely accurate solution.
Visualization of flows by FEM using six‐node triangular element: Free surfaces and flow patterns of an extrusion process
Authors: Shimazaki Yoji 
Published: November 2005

AbstractA simple extrusion process for Newtonian and power‐law fluids is analysed. Marker particles are introduced to analyse the fluid flow motions. Area co‐ordinates of six‐node triangular element are used to determine the marker position in the element. With this element, the solution algorithm becomes simple compared with the one using the linear triangular element. The differences in flow and swell patterns between the two fluids are described.
Massively parallel finite element analysis of coupled, incompressible flows: A benchmark computation of baroclinic annulus waves
Authors: Xiao Qiang , Salinger Andrew G. , Zhou Yuming , Derby Jeffrey J. 
Published: November 2005

AbstractCoupled, three‐dimensional, time‐dependent, incompressible flows in a differentially heated, rotating annulus are simulated using a parallel implementation of the Galerkin finite element method on the Connection Machine 5 (CM‐5) supercomputer. The development of baroclinic annulus waves is computed and found to be consistent with previous experimental reseults. The implementation of a repeated spectral bisection element‐partitioning technique significantly increases the computation speed over a strategy which randomly maps elements to processors, yielding sustained calculation rates of 8.1 GFLOPS on 512 processors of the CM‐5.
Spurious numerical refraction
Authors: Cathers B. , Bates S. 
Published: November 2005

AbstractThe purpose of this paper is to investigate the effect of a non‐uniform mesh in two dimensions (2D). A change in mesh size will, in general, result in spurious refraction (and reflection) which is entirely numerical (rather than physical) in origin. To facilitate the analysis, the mesh geometry has been highly simplified in that only a single change in mesh size is considered. The analysis is based on a finite element wave model.The domain consists of two conterminous regions discernible only by their different nodal spacings in the x‐direction. The interface between the two regions is internal to the mesh and is a straight line. The model is based upon the Crank‐Nicolson linear finite element scheme applied to the second order wave equation. The results of the analysis are confirmed by numerical experiments. It is shown that under particular numerical conditions total internal reflection may occur and when this is the case, the transmitted wave is evanescent. An analysis of the energy flux associated with the incident, reflected and trasmitted waves shows that energy is conserved across the interface between the two regions.
A segregated implicit solution algorithm for 2D and 3D laminar incompressible flows
Authors: Giannakoglou K. C. , Politis E. S. 
Published: November 2005

AbstractA segregated algorithm for the solution of laminar incompressible, two‐ and three‐dimensional flow problems is presented. This algorithm employs the successive solution of the momentum and continuity equations by means of a decoupled implicit solution method. The inversion of the coefficient matrix which is common for all momentum equations is carried out through an approximate factorization in upper and lower triangular matrices. The divergence‐free velocity constraint is satisfied by formulating and solving a pressure correction equation. For the latter a combined application of a preconditioning technique and a Krylov subspace method is employed and proved more effecient than the approximate factorization method. The method exhibits a monotonic convergence, it is not costly in CPU time per iteration and provides accurate solutions which are independent of the underrelaxation parameter used in the momentum equations. Results are presented in two‐ and three‐dimensional flow problems.
Numerical simulation of transient planar flow of a viscoelastic material with two moving free surfaces
Authors: Mao Wenqun , Khayat Roger E. 
Published: November 2005

AbstractIn this study, we examine the numerical simulation of transient viscoelastic flows with two moving free surfaces. A modified Galerkin finite element method is implemented to the two‐dimensional non‐steady motion of the fluid of the Oldroyd‐B type. The fluid is initially placed between two parallel plates and bounded by two straight free boundaries. In this Lagrangian finite element method, the spatial mesh deforms in time along with the moving free boundaries. The unknown shape of the free surfaces is determined with the flow field u, v, τ, p by the deformable finite element method, combined with a predictor‐corrector scheme in an uncoupled fashion. The moving free surfaces and fluid motion of both Newtonian and non‐Newtonian flows are investigated. The results include the influence of surface tension, fluid inertia and elasticity.
Extension of the volume‐of‐fluid method for analysis of free surface viscous flow in an ideal gas
Authors: McKibben John F. , Aidun Cyrus K. 
Published: November 2005

AbstractThe volume‐of‐fluid (VOF) method is a simple and robust technique for simulating free surface flows with large deformations and intersecting free surfaces. Earlier implementations used Laplace's formula for the normal stress boundary condition at the interface between the liquid and vapour phases. We have expanded the interfacial boundary conditions to include the viscous component of the normal stress in the liquid phase and, in a limited manner, to allow the pressure in the vapour phase to vary. Included are sample computations that show the accuracy of added third‐order‐accurate differencing schemes for the convective terms in the Navier‐Stokes equation (NSE), the viscous terms in the normal stress at the interface and the solution of potential flow in the vapour phase coupled with the solution of the NSE in the liquid phase. With these modifications we show that the VOF method can accurately predict the instability of a thin viscous sheet flowing through a stagnant vapour phase.
Labeled Schwann cell transplantation: Cell loss, host Schwann cell replacement, and strategies to enhance survival
Authors: Hill Caitlin E. , Moon Lawrence D.F. , Wood Patrick M. , Bunge Mary Bartlett 
Published: November 2005

AbstractAlthough transplanted Schwann cells (SCs) can promote axon regeneration and remyelination and improve recovery in models of spinal cord injury, little is known about their survival and how they interact with host tissue. Using labeled SCs from transgenic rats expressing human placental alkaline phosphatase (PLAP), SC survival in a spinal cord contusion lesion was assessed. Few PLAP SCs survived at 2 weeks after acute transplantation. They died early due to necrosis and apoptosis. Delaying transplantation until 7 days after injury improved survival. A second wave of cell death occurred after surviving cells had integrated into the spinal cord. Survival of PLAP SCs was enhanced by immunosuppression with cyclosporin; delayed transplantation in conjunction with immunosuppression resulted in the best survival. In all cases, transplantation of SCs resulted in extensive infiltration of endogenous p75+ cells into the injury site, suggesting that endogenous SCs may play an important role in the repair observed after SC transplantation. © 2005 Wiley‐Liss, Inc.
Nuclear phosphoinositide kinases and inositol phospholipids
Authors: Gonzales Michael L. , Anderson Richard A. 
Published: November 2005

AbstractThe presence of inositol phospholipids in the nuclei of mammalian cells has by now been well established, as has the presence of the enzymes responsible for their metabolism. However, our understanding of the role of these nuclear phosphoinositides in regulating cellular events has lagged far behind that for its cytosolic counterpart. It is clear, though, that the nuclear phosphoinositide pool is independent of the cytosolic pool and is, therefore, likely to be regulating a unique set of cellular events. As with its cytosolic phosphoinositides, many nuclear phosphoinositides and their metabolic enzymes are located at distinct sub‐cellular structures. This arrangement spatially limits the production and activity of inositol phospholipids and is believed to be a major mechanism for regulating their function. Here, we will introduce the components of nuclear inositol phospholipid signal transduction and discuss how their spatial arrangement may dictate which nuclear functions they are modulating. © 2005 Wiley‐Liss, Inc.
What determines African bilateral aid receipts?
Authors: McGillivray Mark 
Published: November 2005

AbstractThis paper empirically models aid allocation to four African countries—Egypt, Kenya, Morocco and Tanzania—using 1968–1999 time series data. The econometric method employed allows for the joint determination of aid to these countries and for recipient‐specific coefficients. It is hypothesised that aid to these countries has been determined by a diverse set of determinants, ranging from their developmental needs or requirements through to donor commercial, political and strategic interests. A special interest of the paper is whether policy regimes have impacted on the amounts of aid received by these countries. Results indicate that they have for all four countries, although the direction of influence differs among them. Copyright © 2005 John Wiley & Sons, Ltd.
Application of cross‐linked β‐cyclodextrin polymer for adsorption of aromatic amino acids
Authors: Tang Shouwan , Kong Liang , Ou Junjie , Liu Yueqi , Li Xin , Zou Hanfa 
Published: November 2005

Abstractβ‐Cyclodextrin (β‐CyD) was cross‐linked by hexamethylene diisocyanate and the polymer was investigated for adsorption of aromatic amino acids (AAA) from phosphate buffer. High adsorption rates were observed at the beginning and the adsorption equilibrium was then gradually achieved in about 45 min. The adsorption of AAA decreased with the increase of initial concentration and also temperature. Under the same conditions, the adsorption efficiencies of AAA were in the order of L‐tryptophan (L‐Trp) > L‐phenylalanine (L‐Phe) > L‐tyrosine (L‐Tyr). Much higher adsorption values, up to 52.4 and 43.0 mg/g for L‐Trp and L‐Phe, respectively, at 50 mmol/L and 3.2 mg/g for L‐Tyr at 2 mmol/L, were obtained with the β‐CyD polymer at 37 °C. It was shown that the adsorption of AAA on the β‐CyD polymer was consistent with the Freundlich isotherm equation. The adsorption of mixed aromatic amino acids and branched‐chain amino acids (BCAA) showed that AAA were preferentially adsorbed with adsorption efficiencies 10–24%, while those of BCAA were lower than 2%. It seems that the structure and hydrophobicity of amino acid molecules are responsible for the difference in adsorption, by influencing the strength of interactions between amino acid molecule and the polymer. Copyright © 2005 John Wiley & Sons, Ltd.
Interactions of cationic porphyrins with double‐stranded oligodeoxynucleotides: a study by electrospray ionisation mass spectrometry
Authors: Ramos Catarina I. V. , Barros Cristina M. , Fernandes Ana M. , Santana‐Marques M. G. , Correia A. J. Ferrer , Tomé João P. C. , Carrilho Maria do Carmo T. , Faustino Maria Amparo F. , Tomé Augusto C. , Neves M. G. P. M. S. , Cavaleiro J. A. S. 
Published: November 2005

AbstractElectrospray ionisation mass spectrometry (ESI‐MS), electrospray ionisation tandem mass spectrometry (ESI‐MS/MS) and Ultraviolet‐visible (UV–vis) spectroscopy were used to investigate the non‐covalent interactions between small oligonucleotide duplexes with the GC motif and a group of cationic meso(N‐methylpyridynium‐4‐yl)porphyrins (four free bases with one to four positive charges, and the zinc complex of the tetracationic free base).The results obtained point to outside binding of the porphyrins, with the binding strength increasing with the number of positive charges. Fragmentations involving losses from both chains were observed for the porphyrins with N‐methylpyridinium‐4‐yl groups in opposite meso positions. Copyright © 2005 John Wiley & Sons, Ltd.
Synergistic interaction between 17‐AAG and phosphatidylinositol 3‐kinase inhibition in human malignant glioma cells
Authors: Premkumar Daniel R. , Arnold Beth , Jane Esther P. , Pollack Ian F. 
Published: November 2005

AbstractThe phosphatidylinositol 3′‐kinase (PI3K)/Akt pathway is often constitutively activated in malignant glioma cells, in many cases as a result of mutation of phosphatase and tensin homologue deleted on chromosome ten (PTEN), an endogenous inhibitor of Akt, which renders tumor cells resistant to cytotoxic insults, including those related to anticancer drugs. Pharmacological inhibition of this pathway may potentially restore or augment the effectiveness of conventional chemotherapy or other signaling‐targeted agents. Because the heat shock protein (HSP) is involved in the conformational maturation of a number of signaling proteins critical to the proliferation of malignant glioma cells, we hypothesized that the combination of the PI3K inhibitor LY294002 and the HSP90 inhibitor 17‐allyl‐aminogeldanamycin (17‐AAG) would promote glioma cytotoxicity by decreasing both the activation status and levels of Akt, as well as downregulating the levels of other relevant signaling effectors. We, therefore, examined the effects of LY294002 and 17‐AAG, alone and in combination, on signal transduction and apoptosis in a series of malignant glioma cell lines. Simultaneous exposure to these inhibitors significantly induced cell death, and irreversibly inhibited proliferative activity and colony forming ability of the glioma cell lines. Quantitative analysis revealed that enhancement by LY294002 of 17‐AAG‐induced cytotoxicity was synergistic, leading to a pronounced increase in active caspase‐3 and poly (adenosine diphophate‐ribose) polymerase (PARP) cleavage together with the release of cytochrome c and apoptosis inducing factor (AIF). No significant growth inhibition or caspase activation was seen in control cells. The enhanced cytotoxicity of this combination was associated with diminished Akt activation and a significant downregulation of epidermal growth factor receptor (EGFR), Raf‐1, and mitogen activated protein kinase. Combination of 17‐AAG and LY294002 did not modify phospho‐JNK/SPK and phospho‐p38. Cells exposed to 17‐AAG and LY294002 displayed a significant reduction in cell‐cycle regulatory proteins, such as retinoblastoma (Rb), cyclin dependent kinase (CDK)4, CDK6, cyclin D1, and cyclin D3. Taken together, these findings suggest that the PI3K/Akt pathway plays a critical role in regulating the apoptotic response to 17‐AAG and that targeting this pathway could provide a potent strategy to treat patients with malignant gliomas. © 2005 Wiley‐Liss, Inc.
A study of a non‐linear kinetic model for an ionized gas
Authors: Arlotti Luisa , Bassi Laura , Gamba Patrizia 
Published: November 2005

AbstractA non‐linear one‐dimensional kinetic model for an ionized gas is considered. In this model the collisions between charged and neutral particies and the field generated by the charges are taken into account. The Cauchy problem for the resulting system of equations is examined. An existence and uniqueness theorem of a global in time solution is proved.
Long‐time behaviour of absorbing boundary conditions
Authors: Engquist B. , Halpern L. 
Published: November 2005

AbstractA new class of computational far‐field boundary conditions for hyperbolic partial differential equations was recently introduced by the authors. These boundary conditions combine properties of absorbing conditions for transient solutions and properties of far‐field conditions for steady states. This paper analyses the properties of the wave equation coupled with these new boundary conditions: well‐posedness, dissipativity and convergence in time.
Inversion of the exponential X‐ray transform. II: Numerics
Authors: Hazou Irene A. , Solmon Donald C. 
Published: November 2005

AbstractThe exponential X‐ray transform arises in single photon emission computed tomography and is defined on functions on the plane by 𝒫μf(φ,x) = ∫f (x + tφ)eμt where μ is a constant. In [MMAS(10), 561–574, 1988], we derived analytical formulae for filters K corresponding to a general point spread function E that can be used to invert the exponential X‐ray transform via a filtered backprojection algorithm. Here, we use those formulae to derive expressions suitable for numerical computation of the filters corresponding to a specific family of bandlimited point spread functions and give the results of reconstructions of a mathematical phantom using these filters. Also included is an analogue of the Shepp–Logan ellipse theorem, [IEEE Trans. Nucl. Sci. (21), 21–43, 1974], for the exponential X‐ray transform.