Showing papers on "Dissipation published in 1983"
TL;DR: In this article, the authors focus on an idealized granular material comprised of identical, smooth, imperfectly elastic, spherical particles which is flowing at such a density and is being deformed at a rate that particles interact only through binary collisions with their neighbours.
Abstract: We focus attention on an idealized granular material comprised of identical, smooth, imperfectly elastic, spherical particles which is flowing at such a density and is being deformed at such a rate that particles interact only through binary collisions with their neighbours. Using general forms of the probability distribution functions for the velocity of a single particle and for the likelihood of binary collisions, we derive local expressions for the balance of mass, linear momentum and fluctuation kinetic energy, and integral expressions for the stress, energy flux and energy dissipation that appear in them. We next introduce simple, physically plausible, forms for the probability densities which contain as parameters the mean density, the mean velocity and the mean specific kinetic energy of the velocity fluctuations. This allows us to carry out the integrations for the stress, energy flux and energy dissipation and to express these in terms of the mean fields. Finally, we determine the behaviour of these fields as solutions to the balance laws. As an illustration of this we consider the shear flow maintained between two parallel horizontal plates in relative motion.
1,230 citations
TL;DR: In this paper, the authors reviewed earlier models of random wave transformation and described the transformation of waves, including dissipation due to breaking and bottom friction, by an energy flux balance model, and compared results from random wave experiments in the laboratory and from an extensive set of field measurements.
Abstract: Earlier models of random wave transformation are reviewed in the first section. Then the transformation of waves, including dissipation due to breaking and bottom friction, is described by an energy flux balance model. The wave height pdf of all waves (broken and unbroken) is shown by the field data to be well described by the Rayleigh distribution everywhere. The observed distributions of breaking and broken wave heights are fitted to simple analytical forms, and breaking wave dissipation is calculated by using a periodic bore formulation. The energy flux equation is integrated to yield local values of Hrms as a function of offshore wave conditions. Both analytical and numerical models are developed. In the last section the models are compared with results from random wave experiments in the laboratory and from an extensive set of field measurements.
865 citations
TL;DR: In this paper, a two-dimensional, nonlinear, nonhydrostatic model is described which allows the calculation of moist airflow in mountainous terrain, and the model is compressible, uses a terrain-following coordinate system, and employs lateral and upper boundary conditions which minimize wave reflections.
Abstract: A two-dimensional, nonlinear, nonhydrostatic model is described which allows the calculation of moist airflow in mountainous terrain. The model is compressible, uses a terrain-following coordinate system, and employs lateral and upper boundary conditions which minimize wave reflections. The model's accuracy and sensitivity are examined. These tests suggest that in numerical simulations of vertically propagating, highly nonlinear mountain waves, a wave absorbing layer does not accurately mimic the effects of wave breakdown and dissipation at high levels in the atmosphere. In order to obtain a correct simulation, the region in which the waves are physically absorbed must generally be included in the computational domain (a nonreflective upper boundary condition should be used as well). The utility of the model is demonstrated in two examples (linear waves in a uniform atmosphere and the Jan. 11, 1972 Boulder windstorm) which illustrate how the presence of moisture can influence propagating waves. In both cases, the addition of moisture to the upstream flow greatly reduces the wave response.
375 citations
01 Apr 1983
TL;DR: In this article, a theoretical model for wave heights and set-up in a surf zone is developed for wave flux, radiation stress, and energy dissipation, and the transitions immediately after breaking are analyzed and shown to be in accordance with the above mentioned ideas.
Abstract: A theoretical model is developed for wave heights and set-up in a surf zone. In the time averaged equations of energy and momentum the energy flux, radiation stress and energy dissipation are determined by simple approximations which include the surface roller in the breaker. Comparison with measurements shows good agreement. Also the transitions immediately after breaking are analysed and shown to be in accordance with the above mentioned ideas and results.
354 citations
TL;DR: In this article, the authors report the results of some numerical experiments that bring out the lowpass characteristics of a purely elastic medium with a heterogeneous velocity structure and show that attenuation by intrinsic friction and scattering are approximately additive.
Abstract: We report the results of some numerical experiments that bring out the lowpass characteristics of a purely elastic medium with a heterogeneous velocity structure. Although the typical fluctuation is spatially confined within less than a wavelength, waves propagating over a sufficiently long path suffer major cumulative effects. We summarize the removal of high frequencies during transmission by a frequency-independent apparent Q, and show that attenuation by intrinsic friction and scattering are approximately additive. We propose some diagnostics that might help to distinguish the presence of velocity fluctuations and resultant scattering from the presence of anelasticity and true dissipation. When scattering dominates over intrinsic friction: (1) the coda of a transmitted wave contains relatively higher frequencies than the initial pulse; (2) the attenuation deduced from the power spectrum of the transmitted wave is greater than that deduced from the phase spectrum; (3) compressional and shear wave apparent Q's are approximately equal; and (4) estimates of apparent Q made from reflected coda vary with frequency, while estimates made from the transmitted waves do not. We also outline several topics in the theory of wave propagation that will be relevant in a satisfactory interpretation of short-period observations, if the amplitude of such signals is affected by scattering.
264 citations
183 citations
TL;DR: In this paper, the breakdown of the dissipationless current flow is demonstrated to be spatially localized and transient switching is observed on microsecond time scales among a set of distinct dissipative states.
Abstract: Dynamic nonlinear behavior is reported at high currents in the quantum Hall regime of GaAs heterostructures, resulting from breakdown of the dissipationless current flow. It is demonstrated that this breakdown is spatially localized and transient switching is observed on microsecond time scales among a set of distinct dissipative states. A simple macroscopic picture is proposed to account for these novel phenomena.
182 citations
TL;DR: In this article, an experimental measurement of the efficiency of converting kinetic energy into potential energy through vertical mixing in a continuously stratified fluid was made, showing that the mixing efficiency is only weakly dependent upon Prandtl number provided that this is of order unity or greater.
Abstract: Using experimental measurements, estimates are made of the efficiency of conversion of kinetic energy into potential energy through vertical mixing in a continuously stratified fluid. In the experiments kinetic energy was supplied continuously at a rate of e to a fundamental internal wave mode in a rectangularly bounded and initially linear stable stratification. Mixing resulted from the instability of this wave and its consequent ‘breaking’. Potential energy was gained by the system at rate , were found to have an average for seven runs of 0·24eM, with a standard deviation for the coefficient of 0·1, and no significant correlation with energy supply rate.These results, the first of their kind to correct for incidental losses, substantiate the values previously assumed in estimates of dissipation and vertical diffusion in the ocean and the atmosphere, and validate the assumption of similarity between buoyancy and mass transfer on which they are based. The efficiency value also agrees with the kinematic prediction for localized homogenization in small discrete volumes made in the companion paper (McEwan 1983). On the basis of that work it is inferred from the present results that the mixing efficiency is only weakly dependent upon Prandtl number provided that this is of order unity or greater.
138 citations
TL;DR: In this paper, Bouwa has given a discussion of a severe storm in the southern North Sea, on 3 January 1976 near Texel, one of the Friesian islands, characterized by a remarkable steadiness of wind and wave parameters.
Abstract: Bouwa has given a discussion of a severe storm in the southern North Sea, on 3 January 1976 near Texel, one of the Friesian islands. This storm was characterized by a remarkable steadiness of wind and wave parameters. The steadiness of the wave parameters was apparently the result of depth limitations, which prevented further wave evolution. Here the various terms in the energy balance equation for wave growth in shallow water are estimated. The relative importance of wind input, surface dissipation, bottom dissipation, advection and nonlinear transfer is discussed. For a certain choice of dissipation parameters, a good balance can be obtained. This is in agreement with the steadiness of the observed wave conditions.
114 citations
TL;DR: In this paper, a passive crashworthy system that dissipates impact energy by fracture and plastic deformation of metal tubes is analyzed, where the energy dissipating component is a square tube that is pressed axially against a die where it splits at the corners and curls outward.
95 citations
TL;DR: In this paper, the evolution of the fluctuations arising from the electron drift wave instability is studied in the low-order isotropic k space introduced by Kells and Orszag for the two-dimensional Euler equation.
Abstract: In the low‐order isotropic k space introduced by Kells and Orszag for the two‐dimensional Euler equation, the evolution of the fluctuations arising from the electron drift wave instability is studied. The two‐dimensional drift wave model contains the E×B and polarization drift nonlinearities in the hydrodynamic ions and linear, dissipative electrons. The strength of the electron dissipation is shown to determine the spectral width and the level of the fluctuations.
TL;DR: In this article, the authors provide an analysis for the correct behavior of the dissipation tensor in the Reynolds-stress transport equation in the limit as a wall is approached, which differs from what is used conventionally, and hence is important for turbulence models that include the near wall region.
Abstract: This letter provides an analysis for the correct behavior of the dissipation tensor in the Reynolds‐stress transport equation in the limit as a wall is approached. This differs from what is used conventionally, and hence is important for turbulence models that include the near‐wall region.
27 Mar 1983
TL;DR: In this article, a procedure for obtaining entropy production rates from viscous flow calculations is described, based on process thermodynamics; it allows loss production to be calculated in reversible equilibrium processes.
Abstract: A procedure for obtaining entropy production rates from viscous flow calculations is described. The method is based on process thermodynamics; it allows loss production to be calculated in “irreversible equilibrium processes.”The two-dimensional turbulent boundary layer of Samuel and Joubert is considered. Mean rates of entropy production are evaluated from measured data using rates of dissipation and rates of increase of turbulence kinetic energy. Calculations performed with the Moore Cascade Flow Program give good agreement with mean rates of entropy production and reveal details of the distribution of entropy production throughout the boundary layer. This method is used in Part II to reveal loss sources in calculations for a rectangular elbow.Copyright © 1983 by ASME
TL;DR: In this article, a transport equation for the dissipation rate of mean square scalar variance is proposed to calculate the turnover time scale of the fluctuating velocity and fluctuating scalar fields.
Abstract: In a turbulent flow where the mechanisms and/or the importance of the generation processes of turbulent kinetic energy k and mean square scalar variance ∼(c2) are dissimilar, no simple connection exists between the turnover time scale of the fluctuating velocity and fluctuating scalar fields. To allow the computation of the turbulent scalar field in these situations a means of calculating the scalar time is required. Here, in an extension of work by Newman, Launder, and Lumley [J. Fluid Mech. 111, 217 (1981)], the time scale is obtained via a proposed transport equation for the dissipation rate of mean square scalar variance. The modeled equation has been applied successfully to the calculation of the spread of a thermal mixing layer in grid‐generated turbulence and the decay of temperature variance in a homogeneous field.
TL;DR: In this paper, a nonperturbative, time reversible model of a nuclear system is proposed, which exhibits a dissipative decay of collective motion for times short compared to the system's Poincare time.
TL;DR: In this article, the steady-state velocity of a planar liquid-solid interface is predicted by calculating the free energy dissipated by irreversible processes at the interface and equating it to the available driving free energy.
Abstract: The steady‐state velocity of a planar liquid‐solid interface is predicted by calculating the free energy dissipated by irreversible processes at the interface and equating it to the available driving free energy. A solute drag term and an intrinsic interfacial mobility term are included in the dissipation calculations for a binary alloy. The solute drag calculation employs a solute trapping model, which has been extended to concentrated alloys. The result is presented in terms of a single unknown parameter, the interfacial diffusivity Di. A transition from diffusion controlled to diffusionless solidification occurs over approximately an order of magnitude in growth velocity, as the interface speed surpasses the maximum speed with which solute atoms can diffuse across the interface to remain ahead of the growing crystal.
01 Jan 1983
TL;DR: In this article, it was shown numerically that the long-time asymptotic state in a forced inverse-cascade situation is one in which the spectrum is completely dominated by its own fundamental.
Abstract: It is shown numerically, both for the two-dimensional Navier-Stokes (guiding-center plasma) equations and for two-dimensional magnetohydrodynamics, that the long-time asymptotic state in a forced inverse-cascade situation is one in which the spectrum is completely dominated by its own fundamental. The growth continues until the fundamental is dissipatively limited by its own dissipation rate.
TL;DR: In this paper, an extensive numerical investigation of the dynamics of the driven damped pendulum is conducted and the authors find broad bands of chaotic solutions as a function of the frequency and amplitude of the driving force.
Abstract: The equation of motion of the driven damped pendulum is related at low dissipation to a current-fed Josephson junction and at high dissipation to transport in charge-density-wave (CDW) systems. We report on an extensive numerical investigation of these equations. At low dissipation we find broad bands of chaotic solutions as a function of the frequency and amplitude of the driving force. It is pointed out that periodic solutions may possess a symmetry corresponding to the invariance of the equations of motion under a simultaneous spatial (phase) inversion and a shift in the phase of the driving force by an odd multiple of $\ensuremath{\pi}$. At low dissipation chaos is usually approached via a sequence of period-doubling bifurcations if this symmetry has been broken and directly from period 1 with associated intermittency behavior if the symmetry is not broken. At high dissipation no chaotic behavior is found but broad bands of symmetry-broken solutions, which may be related to recently reported hysteresis phenomena in CDW systems, occur. Discussions of properties of the Poincar\'e maps and of the fractal dimension of the strange attractors associated with the chaotic solutions have been included.
TL;DR: In this paper, the authors used wave formulae derived from the dispersion relation for linear waves to find an analytical solution to the problem of wave height variation on a simple topography; i.e. topographies with incrementally constant slope and straight parallel contours.
TL;DR: In this article, measurements of the advection, production, diffusion and dissipation terms of the mean square temperature fluctuation budget for a two-dimensional jet were presented, and the measured dissipation or destruction, determined using all three components, enables satisfactory closure of the budget in the region of the jet that is free of flow reversal.
TL;DR: In this paper, the Onsager cross-coefficients b1 and b2, coupling growth and heat flow, are calculated for atomically rough surfaces of hcp 4He crystals, based on the premise that growth is limited by the collision of phonons and rotons with the interface.
Abstract: The growth coefficient K (the velocity of growth per unit chemical potential difference) and the Onsager cross-coefficients b1 and b2, coupling growth and heat flow, are calculated for atomically rough surfaces of hcp 4He crystals. The calculation is based on the premise, suggested by Andreev and Parshin, that growth is limited by the collision of phonons and rotons with the interface. The calculated K is compared with that obtained by Keshiskev et al. from the damping of melting-freezing waves. The theory assumes that the excitations are in the ballistic regime where their mean free path is large compared to the wavelength of the melting-freezing waves. In the experiment only the phonons satisfy this condition, yet the theory agrees with the data even when roton scattering is important Irreversible thermodynamics requires that the cross coefficients b1 and b 2 be equal. This is shown by direct calculation. The value of b1 and b2 depends on the ratio of two integrals over the phonon transmission coefficient and it is evaluated for two models of the transmission. The theory agrees fairly well with a recent measurement of b1. A calculation of the dissipation in the hydrodynamic regime, where the free path is short, shows that the damping of melting-freezing waves should have a different dependence on frequency compared to the ballistic regime.
TL;DR: In this article, an area-averaged tidal bottom stress is made for four channel segments of the Great Bay Estuary, N.H. The analysis shows that while throughout the estuary the principal force balance is between the frictional stress and the pressure gradient forcing, RMS values of total bottom stress range from 2·67 to 10·38 Nm−2 and friction coefficients vary from 0·015 to 0·054.
Abstract: Estimates of area-averaged tidal bottom stress are made for four channel segments of the Great Bay Estuary, N.H. Current and sealevel measurements are used to estimate acceleration and pressure gradient terms in the equation of motion, while the equation of motion itself is used to infer the remaining stress term. Dynamic terms, bottom stress values, friction coefficients and energy dissipation rates are estimated for each site. The analysis shows that while throughout the estuary the principal force balance is between the frictional stress and the pressure gradient forcing, RMS values of total bottom stress range from 2·67 to 10·38 Nm−2 and friction coefficients vary from 0·015 to 0·054. Both stress and energy dissipation are largest in the seaward portion of the estuary with an order of magnitude decrease in dissipation at the most inland site. These distributions of stress and energy dissipation are consistent with cotidal charts of the principal semi-diurnal tidal constituent (M2) which indicate that the estuary is composed of a highly dissipative more progressive tidal wave regime seaward and a less dissipative standing wave regime landward.
TL;DR: In this article, the authors examined physical aspects of economic activity, particularly the relationship between economic "organisation" and energy use, and argued that if a physical viewpoint is taken, economies can be considered as self-organizing dissipative systems.
Abstract: This paper examines physical aspects of economic activity, particularly the relationship between economic ‘organisation’ and energy use. The properties of general dissipative systems are explored and the possibility of such systems becoming more organized over time is examined with reference to the second law of thermodynamics and the ‘evolutionary arrow of time’. It is argued that if a physical viewpoint is taken, economies can be considered as self-organizing dissipative systems. Measures of organization and dissipation are proposed and empirical analysis indicates that organization and energy dissipation increase together for economic systems, and there is weaker evidence that energy ‘efficiency’ also increases with organization.
TL;DR: In this paper, a fundamental attempt has been made to split up the common mode (fault) signal and the differential flow signal by integrating two equal Wheatstone bridges on one silicon chip and connecting both bridges in opposite ways with respect to each other.
TL;DR: In this paper, a discussion is presented on the gravitational interaction between ring systems and nearby satellites, where a shepherd satellite lacking damping mechanisms will force oscillations in the motion of a ring particle that are symmetrical with respect to the encounter geometry.
TL;DR: In this article, the conditions of two-phase coexistence in guest-host systems like the metal hydrides are examined, assuming that conversion between the phases dissipates energy.
Abstract: The conditions of two-phase coexistence in guest-host systems like the metal hydrides are examined, assuming that conversion between the phases dissipates energy. It is shown that any such dissipation during phase conversion allows the two phases to coexist over a range of chemical potential and end phase compositions, and hence can account for hysteresis in the metal hydrides. In gas calorimetry the dissipated heat is passed to the outside world through the gas reservoir and is not seen in measured calorimetric heats. The dissipation produces a difference between calorimetric enthalpies of hydride formation and decomposition only indirectly owing to variations in the end phase compositions. However, the dissipation directly affects methods of enthalpy measurement based on temperature variation of chemical potential or composition.
TL;DR: In this article, the authors investigated the dissipated power in a viscoelastic homogeneous sphere having the orbital and physical characteristics of the icy inner satellite of Saturn, Enceladus.
TL;DR: Laterally coherent patches of turbulence were discovered on the upper and lower boundaries of thermohaline intrusions as mentioned in this paper, where the relative importance of turbulence produced by Reynolds stress and that produced by the buoyancy flux of double diffusion was compared.
Abstract: Laterally coherent patches of turbulence were discovered on the upper and lower boundaries of thermohaline intrusions. The ratio ɛ/Jb is used to compare the relative importance of turbulence produced by Reynolds stress and that produced by the buoyancy flux of double diffusion. Velocity profiles show near-inertial motions through the intrusions.
TL;DR: In this paper, the characteristics and structure of power dissipation in Tungsten inert gas (TIG) welding arcs are investigated for argon atmospheres at pressures of up to 135 bar.
Abstract: The characteristics and structure of power dissipation in Tungsten Inert Gas (TIG) welding arcs is investigated for argon atmospheres at pressures of up to 135 bar. Electrical characteristics are reported and probe measurements of local electric field strength and total radiated power have been made. These have been combined to obtain the radially averaged axial dependence of arc properties (e.g. temperature, mass flow rate, plasma velocity and arc radius). It is found that both anode and cathode fall voltages are substantially independent of pressure P while the column electric field strength increases in accordance with P0.5. This is associated with an increase in convective and radiative dissipation from the column such that temperature is little affected by pressure and plasma flow velocity falls. The total energy balance of a 100 A, 10 mm argon arc indicates that convective dissipation accounts for about 70% of column power at all pressures investigated. Radiation consists of 18% at 1 bar increasing to 26% at 20 bar with conduction decreasing in significance with pressure.
TL;DR: In this article, a new class of heat engine is analyzed in which the working fluid operates in a dissipative process, never in equilibrium, and the conditions for stability and for the generation of work are found for operating the general dissipative engine by means of optimal control theory.
Abstract: A new class of heat engine is analyzed in which the working fluid operates in a dissipative process, never in equilibrium. The conditions are found for stability and for the generation of work. Then the optimal path is found for operating the general dissipative engine by means of optimal control theory. The optimal cycle consists of arcs of constant power and of approximately instantaneous adiabats. If the heat flow is a function of temperature only, then the constant power arcs become isotherms. An upper bound is found to the power output. Two examples are worked out in detail: a light‐driven dissipative engine whose absorption is a step function of temperature, and a light‐driven dissipative engine whose working fluid undergoes a chemical reaction (isomerization), absorbing light in the isomeric form favored at high temperatures.