Download or read book A Direct Numerical Simulation of Fully Developed Turbulent Channel Flow with Passive Heat Transfer written by Stephen Lincoln Lyons and published by . This book was released on 1989 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: A direct numerical simulation of a fully developed turbulent channel flow with passive heat transfer is performed. The time-dependent three-dimensional Navier-Stokes equations and advection-diffusion equation are solved numerically using a pseudospectral technique with 1,064,960 grid points in physical space (128 x 65 x 128 in x, y, z). No subgrid scale model is employed since all essential turbulence scales are resolved. The Reynolds number is 2262, based on the half channel height and bulk velocity, and the Prandtl number is 1. The Nusselt number is predicted to be 25.36. A large number of one-point turbulence statistics are computed and compared with existing experimental data taken at similar Reynolds and Nusselt numbers. Agreement with the existing experimental data is excellent except for some discrepancies in the near wall region, y$sp+$ $
Download or read book Large Eddy Simulation of Compressible Turbulent Pipe Flow with Heat Transfer written by Xiaofeng Xu and published by . This book was released on 2003 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: A compressible finite volume formulation for large eddy simulation (LES) of turbulent channel flows was extended to solve the turbulent flows in pipes and annular passages. A general finite volume scheme was developed based on conservation equations in Cartesian coordinates with non-Cartesian control volumes. A dual-time stepping approach with time derivative preconditioning was employed and time marching was done with an implicit lower-upper-symmetric-Gauss-Seidel (LU-SGS) scheme. The small scale motions were modeled by a dynamic subgrid-scale (SGS) model. The code was developed in a multiblock framework and parallelized using the message passing interface (MPI). The finite volume LES formulation was validated by simulating the isothermal fully developed turbulent pipe and annular flows. The results were compared to experimental data and direct numerical simulation (DNS) results. The LES formulation was further validated by the simulation of turbulent pipe flows with low heat transfer and comparisons with passive scalar DNS results. Finally, buoyancy forces were added into the LES formulation to simulate mixed convection in a vertical pipe with constant high wall heat fluxes leading to significant property variations. Step-periodic boundary conditions were studied and implemented. The results were validated by comparing with experimental results. Heating effects and flow laminarization were studied. Excellent agreement with DNS and experimental results were obtained for isothermal turbulent pipe and annular flows. The mean temperature profile for the turbulent pipe flow with low heat transfer matched very well with the DNS passive scalar results. Good matches to constant property correlations were also achieved for friction coefficients and Nusselt numbers. For the mixed convection in a vertical pipe, good agreement with the experimental mean streamwise velocity and temperature profiles was obtained. High heating tended to suppress the turbulent intensities and attenuate the turbulent kinetic energy. The thinner viscous layer led to a larger Nusselt numbers which indicated a higher heat transfer rate. Laminarization phenomena were observed along with large overprediction of friction coefficients and underprediction of Nusselt numbers when comparing to fully turbulent property variation correlations.
Download or read book A Direct Numerical Simulation of Fully Developed Turbulent Channel Flow with Spanwise Wall Oscillation written by Dongmei Zhou and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Square Duct at Low Reynolds Number written by M. Piller and published by . This book was released on 2001 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper, we present the results from Direct Numerical Simulations of turbulent, incompressible flow through a square duct, with an imposed temperature difference between two opposite walls, while the other two walls are assumed perfectly insulated. The mean flow is sustained by an imposed, mean pressure gradient. The most interesting feature, characterizing this geometry, consists in the presence of turbulence-sustained mean secondary motions in the cross-flow plane. In this study, we focus on weak turbulence, in that the Reynolds number, based on bulk velocity and hydraulic diameter, is about 4450. Our results indicate that secondary motions do not affect dramatically the global parameters, like friction factor and Nusselt number, in comparison with the plane-channel flow. This issue is investigated by looking at the distribution of the various contributions to the total heat flux, with particular attention to the mean convective term, which does not appear in the plane channel flow.
Download or read book Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Concentric Annular Pipe written by Edris Bagheri and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the effects of computational domain size and radius ratio on fully developed turbulent flow and heat transfer in a concentric annular pipe are investigated using direct numerical simulation (DNS). To perform DNS, a new parallel computer code based on the pseudo-spectral method was developed using the FORTRAN 90/95 programing languages and the message passing interface (MPI) libraries. In order to study the effects of computational domain size on the turbulence statistics, twelve test cases of different domain sizes are compared. The effects of radius ratio are investigated through a systematic study based on four radius ratios of a concentric pipe. The characteristics of the velocity and temperature fields are examined at two Reynolds number of Re_(D_h ) =8900$ and 17700. The radius ratio affects the interaction of two boundary layers of the concentric annular pipe and has a significant impact on the turbulent flow structures and dynamics. The characteristics of the flow and temperature fields are investigated in both physical and spectral spaces, which include the analyses of the first- and second-order statistical moments, budget balance of the transport equation of Reynolds stresses, two-point correlation coefficients, and premultiplied spectra of velocity, vorticity, and temperature fluctuations. It is observed that the scales and dynamics of turbulence structures vary with the radius ratio as well as the surface curvature of the concave and convex walls. The characteristic length scales of the turbulence structures are identified through a spectral analysis.
Download or read book Turbulent Shear Flows 8 written by Franz Durst and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains a selection of the papers presented at the Eighth Symposium on Turbulent Shear Flows held at the Technical University of Munich, 9-11 September 1991. The first of these biennial international symposia was held at the Pennsylvania State Uni versity, USA, in 1977; subsequent symposia have been held at Imperial College, London, England; the University of California, Davis, USA; the University of Karlsruhe, Ger many; Cornell University, Ithaca, USA; the Paul Sabatier University, Toulouse, France; and Stanford University, California, USA. The purpose of this series of symposia is to provide a forum for the presentation and discussion of new developments in the field of turbulence, especially as related to shear flows of importance in engineering and geo physics. From the 330 extended abstracts submitted for this symposium, 145 papers were presented orally and 60 as posters. Out of these, we have selected twenty-four papers for inclusion in this volume, each of which has been revised and extended in accordance with the editors' recommendations. The following four theme areas were selected after consideration of the quality of the contributions, the importance of the area, and the selection made in earlier volumes: - wall flows, - separated flows, - compressibility effects, - buoyancy, rotation, and curvature effects. As in the past, each section corresponding to the above areas begins with an introduction by an authority in the field that places the individual contributions in context with one another and with related research.
Download or read book Engineering Turbulence Modelling and Experiments 5 written by W. Rodi and published by Elsevier. This book was released on 2002-08-21 with total page 1029 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence is one of the key issues in tackling engineering flow problems. As powerful computers and accurate numerical methods are now available for solving the flow equations, and since engineering applications nearly always involve turbulence effects, the reliability of CFD analysis depends increasingly on the performance of the turbulence models. This series of symposia provides a forum for presenting and discussing new developments in the area of turbulence modelling and measurements, with particular emphasis on engineering-related problems. The papers in this set of proceedings were presented at the 5th International Symposium on Engineering Turbulence Modelling and Measurements in September 2002. They look at a variety of areas, including: Turbulence modelling; Direct and large-eddy simulations; Applications of turbulence models; Experimental studies; Transition; Turbulence control; Aerodynamic flow; Aero-acoustics; Turbomachinery flows; Heat transfer; Combustion systems; Two-phase flows. These papers are preceded by a section containing 6 invited papers covering various aspects of turbulence modelling and simulation as well as their practical application, combustion modelling and particle-image velocimetry.
Download or read book Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Square Duct Roughened with Transverse Or V shaped Ribs written by Seyyed Vahid Mahmoodi Jezeh and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This integrated thesis documents a series of complementary numerical investigations aimed at an improved understanding of turbulent flows and heat transfer in a square duct with ribs of different shapes mounted on one wall. Direct numerical simulation (DNS) is used to accurately resolve the spatial and temporal scales of the simulated flows. The first DNS investigates the turbulent flow in a ribbed square duct of different blockage ratios. The results are compared with those of a smooth duct flow. It is observed that an augmentation of the blockage ratio concurrently generates stronger turbulent secondary flow motions, which drastically alter the turbulent transport processes between the sidewall and duct center, giving rise to high-degrees of non-equilibrium states. The dynamics of coherent structures are studied by examining characteristics of the instantaneous velocity field, swirling strength, spatial two-point auto-correlations, and velocity spectra. The impact of the blockage ratio on the turbulent heat transfer is investigated in the second numerical study. The results show that owing to the existence of the ribs and confinement of the duct, organized secondary flows appear as large streamwise-elongated vortices, which have profound influences on the transport of momentum and thermal energy. This study also shows that the spatial distribution and magnitude of the drag and heat transfer coefficients are highly sensitive to the rib height. The final study focuses on a comparison of highly-disturbed turbulent flows in a square duct with inclined and V-shaped ribs mounted on one wall. The turbulence field is highly sensitive to not only the rib geometry but also the boundary layers developed over the side and top walls. Owing to the difference in the pattern of the cross-stream secondary flow motions of these two ribbed duct cases, the flow physics in the inclined rib case is significantly different from the V-shaped rib case. It is found that near the leeward and windward faces of the ribs, the mean inclination angle of turbulence structures in the V-shaped rib case is greater than that of the inclined rib case, which subsequently enhances momentum transport between the ribbed bottom wall and the smooth top wall.
Download or read book A Selection of Test Cases for the Validation of Large eddy Simulations of Turbulent Flows written by and published by . This book was released on 1998 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Simulation of Turbulent Flow Over a Backward facing Step written by Stanford University. Thermosciences Division. Thermosciences Division and published by . This book was released on 1994 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Approaches and Concepts in Turbulence written by T. Dracos and published by Birkhäuser. This book was released on 2012-12-06 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the proceedings of a colloquium held in Monte Verit from September 9-13, 1991. Special care has been taken to devote adequate space to the scientific discussions, which claimed about half of the time available. Scientists from all over the world presented their views on the importance of kinematic properties, topology and fractal geometry, and on the dynamic behaviour of turbulent flows. They debated the importance of coherent structures and the possibility to incorporate these in the statistical theory of turbulence, as well as their significance for the reduction of the degrees of freedom and the prospective of dynamical systems and chaos approaches to the problem of turbulence. Also under discussion was the relevance of these new approaches to the study of the instability and the origin of turbulence, and the importance of numerical and physical experiments in improving the understanding of turbulence.
Download or read book Direct Numerical Simulation of Curved Turbulent Channel Flow written by Robert deLancey Moser and published by . This book was released on 1984 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Algorithms for the Direct Numerical Simulation of Turbulent Flows Past Compliant Bodies and the Optimization of Highly Constrained PDE Systems written by Anish Avinash Karandikar and published by . This book was released on 2008 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work develops an efficient and accurate new method for direct numerical simulation of laminar and turbulent flow past a circular cylinder with a deformable (compliant) surface. It studies the interaction of the incompressible flow with the compliant cylinder. From the outset, this is defined as an optimization problem, in which we seek to minimize aeroacoustic noise generated by dipole sound sources on the compliant surface at low Mach numbers. We build on a unique method developed in our lab for simulating turbulent flow in a channel with compliant walls. This method is accurate and efficient for large surface deformations. We adapt this method for the cylindrical polar coordinate system to study flow past a compliant cylinder. In this method, a time-dependent coordinate transformation is used to map the deformed flow domain to a regular computational domain. The governing Navier Stokes equations are formulated in the cylindrical polar form and not the contravariant form, as the latter is computationally expensive to simulate. The compliant surface is modeled by a simple spring-mass-damper system. As surface compliance is increased, a decrease in the peak lift coefficient for the compliant cylinder is observed both in the laminar 2D case at Re = 80, as well as the turbulent 3D case at Re = 300. On the other hand, the frequency of vortex shedding and the time-average drag both increase with surface compliance. This work also develops a new method for optimizing highly-constrained PDE systems by splitting up the governing equations into parallel linear programs, thus achieving scalability. It explores optimization of a single-phase fluid heat exchanger to minimize the power required to drive coolant through it by appropriately adjusting the channel width or channel porosity. The Stokes flow in the heat exchanger is modeled as a resistor network, while the flow rate and pressures in the flow are analogous to currents and voltages in the resistor network. The method developed and demonstrated on the resistor network problem extends naturally to the optimization of the variable channel width/porosity distribution in the heat exchanger model.
Download or read book Spectral Methods in Fluid Dynamics written by Claudio Canuto and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a book about spectral methods for partial differential equations: when to use them, how to implement them, and what can be learned from their of spectral methods has evolved rigorous theory. The computational side vigorously since the early 1970s, especially in computationally intensive of the more spectacular applications are applications in fluid dynamics. Some of the power of these discussed here, first in general terms as examples of the methods have been methods and later in great detail after the specifics covered. This book pays special attention to those algorithmic details which are essential to successful implementation of spectral methods. The focus is on algorithms for fluid dynamical problems in transition, turbulence, and aero dynamics. This book does not address specific applications in meteorology, partly because of the lack of experience of the authors in this field and partly because of the coverage provided by Haltiner and Williams (1980). The success of spectral methods in practical computations has led to an increasing interest in their theoretical aspects, especially since the mid-1970s. Although the theory does not yet cover the complete spectrum of applications, the analytical techniques which have been developed in recent years have facilitated the examination of an increasing number of problems of practical interest. In this book we present a unified theory of the mathematical analysis of spectral methods and apply it to many of the algorithms in current use.
Download or read book Turbulent Shear Flows 9 written by Franz Durst and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inaugural Symposium on Turbulent Shear Flows was held at The Pennsylvania State University in 1977. Thereafter the locations for the biennial symposium have alternated between the USA and Europe. However, the ninth Symposium on Turbu lent Shear Flows was awarded to Japan in recognition of the strong support researchers of the Pacific Rim countries have given previous symposia. The University of Kyoto was the host institution and the meeting was held in the Inter national Conference Hall. The Local Arrangements Committee did a superb job scheduling traditional Japanese dinners and arranging visits to the many cultural treasures in the Kyoto region. The meeting attracted more than 260 offers of papers. Thirty-three sessions were scheduled to accommodate the 138 papers accepted for oral presentation. In addition a poster session was scheduled on each of the three days to accommodate a total of 42 poster presentations. From the presentations at the symposium 24 have been selected for inclusion in this volume. The authors of these papers have revised them taking into consideration comments made during their oral presentation and recommendations made by the Editors. Four subject areas are identified, namely closures and fundamentals, free flows, wall flows, and combustion and recirculating flows. Eminent authorities have prepared introductory articles fot each topic to put the individual contributions in context with each other and with related research.
Download or read book Higher level Simulations of Turbulent Flows written by J. H. Ferziger and published by . This book was released on 1981 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: The five major categories of this paper are: Correlations, Integral methods, Reynolds-averaged equations, large eddy simulation, and full simulation.
Download or read book Flow and Heat or Mass Transfer in the Chemical Process Industry written by Dimitrios V. Papavassiliou and published by MDPI. This book was released on 2018-09-28 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Flow and Heat or Mass Transfer in the Chemical Process Industry" that was published in Fluids
