Boundary and inertia effects on flow and heat transfer in porous media

PROTRACED COUNTERINSURGENCY: CHINESE COIN STRATEGY IN XINJIANG by MAJ J. Scott LaRonde, USA, 95 pages. In 1949, following the conclusion of its revolutionary war against the Chinese Nationalist forces, the People’s Liberation Army (PLA) peacefully occupied China’s western most province of Xinjiang. For nearly sixty years, the PLA has conducted a counterinsurgency against several, mostly Uyghur-led, separatist movements. Despite periods of significant violence, particularly in the early 1950s and again in the 1990s, the separatist forces have not gained momentum and remained at a level one insurgency. Mao ZeDeng is revered as a master insurgent and the father of Fourth Generation Warfare. Strategists in armies worldwide study his writings on revolutionary and guerilla warfare. This monograph concludes that Mao, as well as the communist leaders who followed him, was also successful at waging protracted counterinsurgency. For nearly sixty years, separatist movements in Xinjiang, Tibet, and Taiwan have all failed. This monograph analyzes the conflict in Xinjiang and concludes that the Chinese continue to defeat the separatist movement in Xinjiang through a strategy that counters Mao’s seven fundamentals of revolutionary warfare.

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Approved for Public Release; Distribution is Unlimited

Publisher Summary This chapter discusses the mathematical formulation of the problems of convective heat transfer in geothermal systems. Geothermal reservoirs may have numerous near-vertical faults and relatively impermeable intrusive interspersed in the aquifers. Both theoretical and experimental investigations of heat transfer in geothermal systems are reviewed. A qualitative understanding of the large-scale convection processes in a geothermal reservoir and the prediction of reservoir behavior under production can be obtained by idealizing it as a saturated porous medium. The identification of a viable geothermal reservoir and the estimation of its capacity remain major problems in the utilization of geothermal resources. Thermal anomalies in geothermal areas can be detected by surface manifestations, aerial infrared surveys, geochemical analyses, or exploratory drillings. Many of the analyses are applicable to a wide range of engineering problems whenever they can be idealized as convection in a porous medium. These include the problems of the secondary recovery of oil by thermal methods, the use of fibrous materials for thermal insulations, the design of aquifers as an energy storage system, and the deposition of mineral ore in the subsurface formation. Results from short-duration well testing are used to determine reservoir characteristics.

Heat Transfer in Geothermal Systems

This book is written for college juniors and seniors and new graduate students in meteorology, ocean engineering, and oceanography. It begins with a brief overview of what is known about the ocean. This is followed by a description of the ocean basins, for the shape of the seas influences the physical processes in the water. Next, students will study the external forces, wind and heat, acting on the ocean, and the ocean's response. It also includes the equations describing dynamic response of the ocean. For example, the equations of motion, the influence of earth's rotation, and viscosity. Finally, students consider some particular examples: the deep circulation, the equatorial ocean and El NiEœno, and the circulation of particular areas of the ocean. Contents: 1) A Voyage of Discovery. 2) The Historical Setting. 3) The Physical Setting. 4) Atmospheric Influences. 5) The Oceanic Heat Budget. 6) Temperature, Salinity and Density. 7) The Equations of Motion. 8) Equations of Motion with Viscosity. 9) Response of the Upper Ocean to Winds. 10) Geostrophic Currents. 11) Wind Driven Ocean Circulation. 12) Vorticity in the Ocean. 13) Deep Circulation in the Ocean. 14) Equatorial Processes. 15) Numerical Models. 16) Ocean Waves. 17) Coastal Processes and Tides.

Introduction to Physical Oceanography

This book was published in 2004. The Interaction of Ocean Waves and Wind describes in detail the two-way interaction between wind and ocean waves and shows how ocean waves affect weather forecasting on timescales of 5 to 90 days. Winds generate ocean waves, but at the same time airflow is modified due to the loss of energy and momentum to the waves; thus, momentum loss from the atmosphere to the ocean depends on the state of the waves. This volume discusses ocean wave evolution according to the energy balance equation. An extensive overview of nonlinear transfer is given, and as a by-product the role of four-wave interactions in the generation of extreme events, such as freak waves, is discussed. Effects on ocean circulation are described. Coupled ocean-wave, atmosphere modelling gives improved weather and wave forecasts. This volume will interest ocean wave modellers, physicists and applied mathematicians, and engineers interested in shipping and coastal protection.

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The Interaction of Ocean Waves and Wind

For convection in a porous medium the dependence of the Nusselt number on the Rayleigh number is examined to sixth order using an expansion for the Rayleigh number proposed by Kuo (1961). The results show very good agreement with experiment. Additionally, the abrupt change which is observed in the heat transport at a supercritical Rayleigh number may be explained by a breakdown of Darcy's law.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002211207200059X

On steady convection in a porous medium

The boundary-layer regime for convection in a vertical porous layer

Steady wind-drift currents in a deep viscous rotating ocean are studied theoretically. The analysis is based on the Lagrangian description of motion. A mean wind-stress at the surface yields the traditional Ekman current. In addition, the wind-stress is assumed to contain a fluctuating part which transfers energy to the surface waves and compensates for loss due to viscous dissipation. The induced drift due to such waves is investigated. The wave-drift depends on the eddy viscosity as well as the earth's rotation. We assume a fully developed sea, and take the eddy viscosity to be proportional to the friction velocity times a characteristic depth. Hence the total current (Ekman current plus wave-induced current) can be expressed as functions of the wind speed. The results show that the magnitude of the total surface current lies between 3.1 and 3.4% of the wind speed at 10 m height for winds between 5 and 30 m s−1. The deflection angle away from the wind direction varies from 23 to 30° in this ran...

Steady wind- and wave-induced currents in the open ocean

Surface gravity waves in a viscous rotating ocean are studied theoretically when they penetrate an area covered by highly concentrated brashlike ice. The motion is described by a Lagrangian formulation, and the brash is modeled by a viscous Newtonian fluid. Results for wave attenuation and wave drift are obtained in the asymptotic limit of a thin, very viscous upper layer. The derived damping rate compares favorably with field data from the marginal ice zone (MIZ). The drift velocity in the ocean exhibits a marked maximum in the viscous boundary layer near the ice-ocean interface. At the outer edge of the boundary layer it exceeds the inviscid Stokes drift by a factor of 7/4. Computed values for the mean viscous drag on the ice induced by the wave motion show that this effect may compete with the frictional effected of the wind in packing the ice. Finally it is demonstrated that the integrated horizontal mass transports in the open ocean and under the ice do not match, which leads to upwelling in...

Jan Erik H. Weber

Papers

On steady convection in a porous medium

The boundary-layer regime for convection in a vertical porous layer

Steady wind- and wave-induced currents in the open ocean

Wave Attenuation and Wave Drift in the Marginal Ice Zone

Convection in a porous medium with horizontal and vertical temperature gradients