Author: Kyle Ashley Brucker
Publisher:
ISBN:
Category :
Languages : en
Pages : 180
Book Description
The dissertation focuses on a comparison between momentumless (self-propelled) and net-momentum (towed) wakes with an emphasis on the elucidation of buoyancy effects. It is difficult to realize truly momentumless wakes in the laboratory and DNS offer a viable, accurate alternative because the initial value of net momentum can be controlled and the evolution of the net momentum can be closely monitored. DNS of axisymmetric wakes with and without net momentum are performed at Re=50,000 on a grid with approximately 2 billion grid points. The development of the wake is characterized by the evolution of maxima, area integrals and spatial distributions of mean and turbulence statistics. The mean velocity in the self-propelled, momentumless wake decays more rapidly than the towed case due to higher shear and consequently a faster rate of energy transfer to turbulence. Buoyancy allows a wake to survive longer in a stratified fluid by reducing the u1'u3' correlation responsible for the mean-to-turbulence energy transfer in the vertical direction. This buoyancy effect is especially important in the self-propelled case because it allows regions of positive and negative momentum to become decoupled in the vertical direction and decay with different rates. The vertical wake thickness is found to be larger in self-propelled wakes. The role of internal waves in the energetics is determined and it is found that they are responsible for sustaining turbulence at the wake periphery long after the shear production has subsided. The non-equilibrium region of the Re=50,000 wake is found to exhibit a time span when, although the turbulence is strongly stratified as indicated by small Froude number, the turbulent dissipation rate exhibits inertial scaling. The multiply inflected mean velocity profile, inherent to the self-propelled wake, results in four bands of vorticity, compared to the two bands observed in the towed case. Vortex pairs of opposite sign form vortex dipoles which interact with other dipoles to cause a more disordered appearance of the late wake vorticity when compared to the towed case.
Numerical Investigation of Momentumless Wakes in Stratified Fluids
Author: Kyle Ashley Brucker
Publisher:
ISBN:
Category :
Languages : en
Pages : 180
Book Description
The dissertation focuses on a comparison between momentumless (self-propelled) and net-momentum (towed) wakes with an emphasis on the elucidation of buoyancy effects. It is difficult to realize truly momentumless wakes in the laboratory and DNS offer a viable, accurate alternative because the initial value of net momentum can be controlled and the evolution of the net momentum can be closely monitored. DNS of axisymmetric wakes with and without net momentum are performed at Re=50,000 on a grid with approximately 2 billion grid points. The development of the wake is characterized by the evolution of maxima, area integrals and spatial distributions of mean and turbulence statistics. The mean velocity in the self-propelled, momentumless wake decays more rapidly than the towed case due to higher shear and consequently a faster rate of energy transfer to turbulence. Buoyancy allows a wake to survive longer in a stratified fluid by reducing the u1'u3' correlation responsible for the mean-to-turbulence energy transfer in the vertical direction. This buoyancy effect is especially important in the self-propelled case because it allows regions of positive and negative momentum to become decoupled in the vertical direction and decay with different rates. The vertical wake thickness is found to be larger in self-propelled wakes. The role of internal waves in the energetics is determined and it is found that they are responsible for sustaining turbulence at the wake periphery long after the shear production has subsided. The non-equilibrium region of the Re=50,000 wake is found to exhibit a time span when, although the turbulence is strongly stratified as indicated by small Froude number, the turbulent dissipation rate exhibits inertial scaling. The multiply inflected mean velocity profile, inherent to the self-propelled wake, results in four bands of vorticity, compared to the two bands observed in the towed case. Vortex pairs of opposite sign form vortex dipoles which interact with other dipoles to cause a more disordered appearance of the late wake vorticity when compared to the towed case.
Publisher:
ISBN:
Category :
Languages : en
Pages : 180
Book Description
The dissertation focuses on a comparison between momentumless (self-propelled) and net-momentum (towed) wakes with an emphasis on the elucidation of buoyancy effects. It is difficult to realize truly momentumless wakes in the laboratory and DNS offer a viable, accurate alternative because the initial value of net momentum can be controlled and the evolution of the net momentum can be closely monitored. DNS of axisymmetric wakes with and without net momentum are performed at Re=50,000 on a grid with approximately 2 billion grid points. The development of the wake is characterized by the evolution of maxima, area integrals and spatial distributions of mean and turbulence statistics. The mean velocity in the self-propelled, momentumless wake decays more rapidly than the towed case due to higher shear and consequently a faster rate of energy transfer to turbulence. Buoyancy allows a wake to survive longer in a stratified fluid by reducing the u1'u3' correlation responsible for the mean-to-turbulence energy transfer in the vertical direction. This buoyancy effect is especially important in the self-propelled case because it allows regions of positive and negative momentum to become decoupled in the vertical direction and decay with different rates. The vertical wake thickness is found to be larger in self-propelled wakes. The role of internal waves in the energetics is determined and it is found that they are responsible for sustaining turbulence at the wake periphery long after the shear production has subsided. The non-equilibrium region of the Re=50,000 wake is found to exhibit a time span when, although the turbulence is strongly stratified as indicated by small Froude number, the turbulent dissipation rate exhibits inertial scaling. The multiply inflected mean velocity profile, inherent to the self-propelled wake, results in four bands of vorticity, compared to the two bands observed in the towed case. Vortex pairs of opposite sign form vortex dipoles which interact with other dipoles to cause a more disordered appearance of the late wake vorticity when compared to the towed case.
Mathematical Models and Integration Methods
Author: Oleg V. Kaptsov
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 3111546667
Category : Mathematics
Languages : en
Pages : 180
Book Description
The book compiles works presented at a seminar aiming to attract global experts in differential equations, mathematical modeling, and integration methods. It covers classical and contemporary integration techniques for partial differential equations, including Monge and Darboux's approaches and their extensions. Additionally, it introduces a novel theoretical model for plane turbulent flows, presents gravitational equations derived from the principle of least action, and explores symmetry-preserving conservative finite-difference schemes for hydrodynamic-type equations. Analytical solutions for Maxwell's equations in incompressible viscoelastic mediums are examined, alongside theoretical-group analysis of wake mathematical models and reduction to ordinary differential equations. The book also delves into special classes of two-dimensional ideal fluid motion and advancements in discrete orthogonal polynomial theory, showcasing rapid decay properties near interval boundaries. In conclusion, this comprehensive collection is indispensable for researchers and practitioners in applied mathematics, fluid dynamics, and computational modeling, providing valuable insights into cutting-edge methods and solutions in the field.
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 3111546667
Category : Mathematics
Languages : en
Pages : 180
Book Description
The book compiles works presented at a seminar aiming to attract global experts in differential equations, mathematical modeling, and integration methods. It covers classical and contemporary integration techniques for partial differential equations, including Monge and Darboux's approaches and their extensions. Additionally, it introduces a novel theoretical model for plane turbulent flows, presents gravitational equations derived from the principle of least action, and explores symmetry-preserving conservative finite-difference schemes for hydrodynamic-type equations. Analytical solutions for Maxwell's equations in incompressible viscoelastic mediums are examined, alongside theoretical-group analysis of wake mathematical models and reduction to ordinary differential equations. The book also delves into special classes of two-dimensional ideal fluid motion and advancements in discrete orthogonal polynomial theory, showcasing rapid decay properties near interval boundaries. In conclusion, this comprehensive collection is indispensable for researchers and practitioners in applied mathematics, fluid dynamics, and computational modeling, providing valuable insights into cutting-edge methods and solutions in the field.
Marine Propulsors
Author: Sverre Steen
Publisher: MDPI
ISBN: 3038972029
Category : Technology & Engineering
Languages : en
Pages : 355
Book Description
This book is a printed edition of the Special Issue "Marine Propulsors" that was published in JMSE
Publisher: MDPI
ISBN: 3038972029
Category : Technology & Engineering
Languages : en
Pages : 355
Book Description
This book is a printed edition of the Special Issue "Marine Propulsors" that was published in JMSE
Computational Science and High Performance Computing III
Author: Egon Krause
Publisher: Springer Science & Business Media
ISBN: 3540690107
Category : Technology & Engineering
Languages : en
Pages : 258
Book Description
This volume contains 18 contributions to the Third Russian-German Advanced Research Workshop on Computational Science and High Performance Computing presented in July 2007 at Novosibirsk, Russia. The workshop was organized jointly by the High Performance Computing Center Stuttgart (HLRS) and the Institute of Computational Technologies of the Siberian Branch of the Russian Academy of Sciences (ICT SB RAS) The contributions range from computer science, mathematics and high performance computing to applications in mechanical and aerospace engineering. They show a wealth of theoretical work and simulation experience with a potential of bringing together theoretical mathematical modelling and usage of high performance computing systems presenting the state of the art of computational technologies.
Publisher: Springer Science & Business Media
ISBN: 3540690107
Category : Technology & Engineering
Languages : en
Pages : 258
Book Description
This volume contains 18 contributions to the Third Russian-German Advanced Research Workshop on Computational Science and High Performance Computing presented in July 2007 at Novosibirsk, Russia. The workshop was organized jointly by the High Performance Computing Center Stuttgart (HLRS) and the Institute of Computational Technologies of the Siberian Branch of the Russian Academy of Sciences (ICT SB RAS) The contributions range from computer science, mathematics and high performance computing to applications in mechanical and aerospace engineering. They show a wealth of theoretical work and simulation experience with a potential of bringing together theoretical mathematical modelling and usage of high performance computing systems presenting the state of the art of computational technologies.
Handbook of Turbulence
Author: Walter Frost
Publisher: Springer Science & Business Media
ISBN: 1468423223
Category : Technology & Engineering
Languages : en
Pages : 511
Book Description
Turbulence takes place in practically all flow situations that occur naturally or in modern technological systems. Therefore, considerable effort is being expended in an attempt to understand this very complex physical phenome non and to develop both empirical and mathematical models for its description. Such numerical and analytical computational schemes would allow the reliable prediction and design of turbulent flow processes to be carried out. The purpose of this book is to bring together, in a usable form, some of the fundamental concepts of turbulence along with turbulence models and experimental techniques. It is hoped that these have "general applicability" in current engineering design. The phrase "general applicabil ity" is highlighted because the theory of turbulence is still so much in a formative stage that completely general analyses are not available now, nor will they be available in the immediate future. The concepts and models described herein represent the state-of-the art methods that are now being used to give answers to turbulent flow problems. As in all turbulent flow analysis, the methods are a blend of analytical and empirical input, and the reader should be cognizant of the simplification and restrictions imposed upon the methods when applyingthem to physical situations different from those for which they have been developed.
Publisher: Springer Science & Business Media
ISBN: 1468423223
Category : Technology & Engineering
Languages : en
Pages : 511
Book Description
Turbulence takes place in practically all flow situations that occur naturally or in modern technological systems. Therefore, considerable effort is being expended in an attempt to understand this very complex physical phenome non and to develop both empirical and mathematical models for its description. Such numerical and analytical computational schemes would allow the reliable prediction and design of turbulent flow processes to be carried out. The purpose of this book is to bring together, in a usable form, some of the fundamental concepts of turbulence along with turbulence models and experimental techniques. It is hoped that these have "general applicability" in current engineering design. The phrase "general applicabil ity" is highlighted because the theory of turbulence is still so much in a formative stage that completely general analyses are not available now, nor will they be available in the immediate future. The concepts and models described herein represent the state-of-the art methods that are now being used to give answers to turbulent flow problems. As in all turbulent flow analysis, the methods are a blend of analytical and empirical input, and the reader should be cognizant of the simplification and restrictions imposed upon the methods when applyingthem to physical situations different from those for which they have been developed.
NBS Special Publication
Author:
Publisher:
ISBN:
Category : Weights and measures
Languages : en
Pages : 1164
Book Description
Publisher:
ISBN:
Category : Weights and measures
Languages : en
Pages : 1164
Book Description
Report
Author: United States. National Bureau of Standards
Publisher:
ISBN:
Category : Hydraulic engineering
Languages : en
Pages : 696
Book Description
Publisher:
ISBN:
Category : Hydraulic engineering
Languages : en
Pages : 696
Book Description
Current Hydraulic Laboratory Research in the United States
Author:
Publisher:
ISBN:
Category : Hydraulic engineering
Languages : en
Pages : 334
Book Description
Publisher:
ISBN:
Category : Hydraulic engineering
Languages : en
Pages : 334
Book Description
Hydraulic Research in the United States 1968
Author: United States. National Bureau of Standards
Publisher:
ISBN:
Category : Hydraulic engineering
Languages : en
Pages : 342
Book Description
Publisher:
ISBN:
Category : Hydraulic engineering
Languages : en
Pages : 342
Book Description