The Experts below are selected from a list of 2343 Experts worldwide ranked by ideXlab platform
Noack, Bernd R. - One of the best experts on this subject based on the ideXlab platform.
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Control Volume Analysis, Entropy Balance and the Entropy Production in Flow Systems
2014Co-Authors: Niven, Robert K., Noack, Bernd R.Abstract:This chapter concerns "control volume analysis", the standard engineering tool for the analysis of flow systems, and its application to entropy balance calculations. Firstly, the principles of control volume analysis are enunciated and applied to flows of conserved quantities (e.g. mass, momentum, energy) through a control volume, giving integral (Reynolds transport theorem) and differential forms of the conservation equations. Several definitions of steady state are discussed. The concept of "entropy" is then established using Jaynes' maximum entropy method, both in general and in equilibrium thermodynamics. The thermodynamic entropy then gives the "entropy production" concept. Equations for the entropy production are then derived for simple, integral and Infinitesimal flow systems. Some technical aspects are examined, including discrete and continuum representations of volume Elements, the effect of radiation, and the analysis of systems subdivided into compartments. A Reynolds decomposition of the entropy production equation then reveals an "entropy production closure problem" in fluctuating dissipative systems: even at steady state, the entropy production based on mean flow rates and gradients is not necessarily in balance with the outward entropy fluxes based on mean quantities. Finally, a direct analysis of an Infinitesimal Element by Jaynes' maximum entropy method yields a theoretical framework with which to predict the steady state of a flow system. This is cast in terms of a "minimum flux potential" principle, which reduces, in different circumstances, to maximum or minimum entropy production (MaxEP or MinEP) principles. It is hoped that this chapter inspires others to attain a deeper understanding and higher technical rigour in the calculation and extremisation of the entropy production in flow systems of all types.Comment: Reference: Niven, R.K. and Noack, B.R. (2013), Control volume analysis, entropy balance and the entropy production in flow systems, in Dewar R.C., Lineweaver C., Niven R.K., Regenauer-Lieb K., Beyond the Second Law: Entropy Production and Non-Equilibrium Systems, Springer-Verlag, Berlin, Heidelberg, ISBN 978-3-642-40153-4, pp 129-16
Bernd R. Noack - One of the best experts on this subject based on the ideXlab platform.
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Control Volume Analysis, Entropy Balance and the Entropy Production in Flow Systems
Understanding Complex Systems, 2013Co-Authors: Robert K. Niven, Bernd R. NoackAbstract:This chapter concerns “control volume analysis”, the standard engineering tool for the analysis of flow systems, and its application to entropy balance calculations. Firstly, the principles of control volume analysis are enunciated and applied to flows of conserved quantities (e.g. mass, momentum, energy) through a control volume, giving integral (Reynolds transport theorem) and differential forms of the conservation equations. Several definitions of steady state are discussed. The concept of “entropy” is then established using Jaynes’ maximum entropy method, both in general and in equilibrium thermodynamics. The thermodynamic entropy then gives the “entropy production” concept. Equations for the entropy production are then derived for simple, integral and Infinitesimal flow systems. Some technical aspects are examined, including discrete and continuum representations of volume Elements, the effect of radiation, and the analysis of systems subdivided into compartments. A Reynolds decomposition of the entropy production equation then reveals an “entropy production closure problem” in fluctuating dissipative systems: even at steady state, the entropy production based on mean flow rates and gradients is not necessarily in balance with the outward entropy fluxes based on mean quantities. Finally, a direct analysis of an Infinitesimal Element by Jaynes’ maximum entropy method yields a theoretical framework with which to predict the steady state of a flow system. This is cast in terms of a “minimum flux potential” principle, which reduces, in different circumstances, to maximum or minimum entropy production (MaxEP or MinEP) principles. It is hoped that this chapter inspires others to attain a deeper understanding and higher technical rigour in the calculation and extremisation of the entropy production in flow systems of all types.
Ma Yingchao - One of the best experts on this subject based on the ideXlab platform.
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Working mechanism of helix angle on peak cutting forces together with its design theory for peripheral milling tools
Journal of Materials Processing Technology, 2017Co-Authors: Min Wan, Jia Feng, Weihong Zhang, Yun Yang, Ma YingchaoAbstract:Abstract Existing researches for studying the influences of mill's helix angle on peak cutting force were mainly carried out by using simulation or experimental means. Thus, the obtained conclusions were just empirical judgments or qualitative observations, which cannot be further used for optimally designing the helix angle of mills. This paper presents a theoretical method for the first time to reveal the working mechanism of peripheral milling tool's helix angle on peak cutting force through strict analytical formulation. To facilitate well understanding the effect of helix angle, variation tendency of peak cutting force versus helix angle is comprehensively studied by analyzing the formation principle of peak cutting force from the point view of both geometrical explanation and theoretical proof. Both Infinitesimal Element method and differential theory are used in the investigation procedure. It is proved that the peak value of cutting forces decreases with the increase of helix angle for a single engaged cutting edge. Combining this conclusion with the overlapping effect of multiple engaged cutting edges, optimal helix angle corresponding to the minimum of peak cutting forces is analytically derived to be the function of axial depth of cut, number of flutes and cutter diameter. Experimental verifications have been carried out to validate the proposed theory.
Niven, Robert K. - One of the best experts on this subject based on the ideXlab platform.
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Control Volume Analysis, Entropy Balance and the Entropy Production in Flow Systems
2014Co-Authors: Niven, Robert K., Noack, Bernd R.Abstract:This chapter concerns "control volume analysis", the standard engineering tool for the analysis of flow systems, and its application to entropy balance calculations. Firstly, the principles of control volume analysis are enunciated and applied to flows of conserved quantities (e.g. mass, momentum, energy) through a control volume, giving integral (Reynolds transport theorem) and differential forms of the conservation equations. Several definitions of steady state are discussed. The concept of "entropy" is then established using Jaynes' maximum entropy method, both in general and in equilibrium thermodynamics. The thermodynamic entropy then gives the "entropy production" concept. Equations for the entropy production are then derived for simple, integral and Infinitesimal flow systems. Some technical aspects are examined, including discrete and continuum representations of volume Elements, the effect of radiation, and the analysis of systems subdivided into compartments. A Reynolds decomposition of the entropy production equation then reveals an "entropy production closure problem" in fluctuating dissipative systems: even at steady state, the entropy production based on mean flow rates and gradients is not necessarily in balance with the outward entropy fluxes based on mean quantities. Finally, a direct analysis of an Infinitesimal Element by Jaynes' maximum entropy method yields a theoretical framework with which to predict the steady state of a flow system. This is cast in terms of a "minimum flux potential" principle, which reduces, in different circumstances, to maximum or minimum entropy production (MaxEP or MinEP) principles. It is hoped that this chapter inspires others to attain a deeper understanding and higher technical rigour in the calculation and extremisation of the entropy production in flow systems of all types.Comment: Reference: Niven, R.K. and Noack, B.R. (2013), Control volume analysis, entropy balance and the entropy production in flow systems, in Dewar R.C., Lineweaver C., Niven R.K., Regenauer-Lieb K., Beyond the Second Law: Entropy Production and Non-Equilibrium Systems, Springer-Verlag, Berlin, Heidelberg, ISBN 978-3-642-40153-4, pp 129-16
Robert K. Niven - One of the best experts on this subject based on the ideXlab platform.
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Control Volume Analysis, Entropy Balance and the Entropy Production in Flow Systems
Understanding Complex Systems, 2013Co-Authors: Robert K. Niven, Bernd R. NoackAbstract:This chapter concerns “control volume analysis”, the standard engineering tool for the analysis of flow systems, and its application to entropy balance calculations. Firstly, the principles of control volume analysis are enunciated and applied to flows of conserved quantities (e.g. mass, momentum, energy) through a control volume, giving integral (Reynolds transport theorem) and differential forms of the conservation equations. Several definitions of steady state are discussed. The concept of “entropy” is then established using Jaynes’ maximum entropy method, both in general and in equilibrium thermodynamics. The thermodynamic entropy then gives the “entropy production” concept. Equations for the entropy production are then derived for simple, integral and Infinitesimal flow systems. Some technical aspects are examined, including discrete and continuum representations of volume Elements, the effect of radiation, and the analysis of systems subdivided into compartments. A Reynolds decomposition of the entropy production equation then reveals an “entropy production closure problem” in fluctuating dissipative systems: even at steady state, the entropy production based on mean flow rates and gradients is not necessarily in balance with the outward entropy fluxes based on mean quantities. Finally, a direct analysis of an Infinitesimal Element by Jaynes’ maximum entropy method yields a theoretical framework with which to predict the steady state of a flow system. This is cast in terms of a “minimum flux potential” principle, which reduces, in different circumstances, to maximum or minimum entropy production (MaxEP or MinEP) principles. It is hoped that this chapter inspires others to attain a deeper understanding and higher technical rigour in the calculation and extremisation of the entropy production in flow systems of all types.