Development of code evaluation criteria for assessing predictive capability and performance

Computational Fluid Dynamics (CFD), because of its unique ability to predict complex three-dimensional flows, is being applied with increasing frequency in the aerospace industry. Currently, no consistent code validation procedure is applied within the industry. Such a procedure is needed to increase confidence in CFD and reduce risk in the use of these codes as a design and analysis tool. This final contract report defines classifications for three levels of code validation, directly relating the use of CFD codes to the engineering design cycle. Evaluation criteria by which codes are measured and classified are recommended and discussed. Criteria for selecting experimental data against which CFD results can be compared are outlined. A four phase CFD code validation procedure is described in detail. Finally, the code validation procedure is demonstrated through application of the REACT CFD code to a series of cases culminating in a code to data comparison on the Space Shuttle Main Engine High Pressure Fuel Turbopump Impeller

Aerodynamic Methods for Estimating Turbulent Fluxes

The exchange of energy and mass between a surface and the lowest region of the troposphere is a complex process that governs many hydrological, agricultural, and atmospheric processes. The layer of air directly affected by surface– atmosphere exchanges is strongly influenced by turbulent processes at the surface–atmosphere boundary and extends upward into the atmosphere to a height of approximately 1 km. This region is commonly referred to as the atmospheric boundary layer (ABL) that is uniquely characterized by turbulence resulting from mechanical (wind shear) and buoyancy (thermal) forces at or near the surface. Methods have been developed to evaluate energy/mass (heat, water vapor, trace gases, and pollutants) exchanges between the ABL and the underlying surface. In this chapter, we describe the flux gradient approach for estimating mass and energy fluxes under the rubric of aerodynamic methods. We provide some historical perspective, present fundamental equations in the context of Monin-Obukhov similarity theory and introduce recent developments of an alternative method to compute heat and water vapor fluxes using turbulence variance statistics

Aerodynamic Methods for Estimating Turbulent Fluxes

The exchange of energy and mass between a surface and the lowest region of the troposphere is a complex process that governs many hydrological, agricultural, and atmospheric processes. The layer of air directly affected by surface– atmosphere exchanges is strongly influenced by turbulent processes at the surface–atmosphere boundary and extends upward into the atmosphere to a height of approximately 1 km. This region is commonly referred to as the atmospheric boundary layer (ABL) that is uniquely characterized by turbulence resulting from mechanical (wind shear) and buoyancy (thermal) forces at or near the surface. Methods have been developed to evaluate energy/mass (heat, water vapor, trace gases, and pollutants) exchanges between the ABL and the underlying surface. In this chapter, we describe the flux gradient approach for estimating mass and energy fluxes under the rubric of aerodynamic methods. We provide some historical perspective, present fundamental equations in the context of Monin-Obukhov similarity theory and introduce recent developments of an alternative method to compute heat and water vapor fluxes using turbulence variance statistics

Temperature extremes: Effect on plant growth and development

AbstractTemperature is a primary factor affecting the rate of plant development. Warmer temperatures expected with climate change and the potential for more extreme temperature events will impact plant productivity. Pollination is one of the most sensitive phenological stages to temperature extremes across all species and during this developmental stage temperature extremes would greatly affect production. Few adaptation strategies are available to cope with temperature extremes at this developmental stage other than to select for plants which shed pollen during the cooler periods of the day or are indeterminate so flowering occurs over a longer period of the growing season. In controlled environment studies, warm temperatures increased the rate of phenological development; however, there was no effect on leaf area or vegetative biomass compared to normal temperatures. The major impact of warmer temperatures was during the reproductive stage of development and in all cases grain yield in maize was significantly reduced by as much as 80−90% from a normal temperature regime. Temperature effects are increased by water deficits and excess soil water demonstrating that understanding the interaction of temperature and water will be needed to develop more effective adaptation strategies to offset the impacts of greater temperature extreme events associated with a changing climate

"Cuba: el yugo, la sangre y el fuego" : Análisis de la táctica y estrategia del Ejercito Rebelde frente al "Plan FF" desde Clausewitz y Tse-tung

El objetivo de este trabajo es analizar las correspondencias entre algunos de los principios teóricos de guerra centrales postulados por Carl Von Clausewitz y Mao Tsetung de manera comparada con el plan estratégico de victoria militar y el conjunto de decisiones tácticas ejecutado por el Ejercito Rebelde y el Movimiento 26 de Julio contra el Ejercito de Batista, en lo que se conoció mas tarde como el "Plan FF", en el marco de la Revolución Cubana. Para poder limitarnos a las pretensiones esperadas por la catedra, recortaremos temporalmente este enfrentamiento estratégico a una etapa dentro del momento que el mismo Fidel Castro denomino "La ofensiva estratégica" u "ofensiva de verano". La etapa dentro de este momento es aquella en la cual el líder de la revolución señala que "la iniciativa correspondió totalmente al enemigo". Precisando el recorte temporal, el mismo se limita a los sucesos ocurridos en la Sierra Maestra entre los días 25 de mayo y 23 de junio del año 1958. Sin embargo -en términos de planificación, las disyuntivas tácticas, y las respectivas tomas de decisiones- vamos a remontarnos posiblemente a días previos al recorte temporal señalado.Mesa 23: La guerra como objeto de estudio de las ciencias humanas. Problemas teóricos y abordajes de conflictos concretos, de la antigüedad al presenteFacultad de Humanidades y Ciencias de la Educació

"Cuba: el yugo, la sangre y el fuego" : Análisis de la táctica y estrategia del Ejercito Rebelde frente al "Plan FF" desde Clausewitz y Tse-tung

El objetivo de este trabajo es analizar las correspondencias entre algunos de los principios teóricos de guerra centrales postulados por Carl Von Clausewitz y Mao Tsetung de manera comparada con el plan estratégico de victoria militar y el conjunto de decisiones tácticas ejecutado por el Ejercito Rebelde y el Movimiento 26 de Julio contra el Ejercito de Batista, en lo que se conoció mas tarde como el "Plan FF", en el marco de la Revolución Cubana. Para poder limitarnos a las pretensiones esperadas por la catedra, recortaremos temporalmente este enfrentamiento estratégico a una etapa dentro del momento que el mismo Fidel Castro denomino "La ofensiva estratégica" u "ofensiva de verano". La etapa dentro de este momento es aquella en la cual el líder de la revolución señala que "la iniciativa correspondió totalmente al enemigo". Precisando el recorte temporal, el mismo se limita a los sucesos ocurridos en la Sierra Maestra entre los días 25 de mayo y 23 de junio del año 1958. Sin embargo -en términos de planificación, las disyuntivas tácticas, y las respectivas tomas de decisiones- vamos a remontarnos posiblemente a días previos al recorte temporal señalado.Mesa 23: La guerra como objeto de estudio de las ciencias humanas. Problemas teóricos y abordajes de conflictos concretos, de la antigüedad al presenteFacultad de Humanidades y Ciencias de la Educació

"Cuba: el yugo, la sangre y el fuego" : Análisis de la táctica y estrategia del Ejercito Rebelde frente al "Plan FF" desde Clausewitz y Tse-tung

El objetivo de este trabajo es analizar las correspondencias entre algunos de los principios teóricos de guerra centrales postulados por Carl Von Clausewitz y Mao Tsetung de manera comparada con el plan estratégico de victoria militar y el conjunto de decisiones tácticas ejecutado por el Ejercito Rebelde y el Movimiento 26 de Julio contra el Ejercito de Batista, en lo que se conoció mas tarde como el "Plan FF", en el marco de la Revolución Cubana. Para poder limitarnos a las pretensiones esperadas por la catedra, recortaremos temporalmente este enfrentamiento estratégico a una etapa dentro del momento que el mismo Fidel Castro denomino "La ofensiva estratégica" u "ofensiva de verano". La etapa dentro de este momento es aquella en la cual el líder de la revolución señala que "la iniciativa correspondió totalmente al enemigo". Precisando el recorte temporal, el mismo se limita a los sucesos ocurridos en la Sierra Maestra entre los días 25 de mayo y 23 de junio del año 1958. Sin embargo -en términos de planificación, las disyuntivas tácticas, y las respectivas tomas de decisiones- vamos a remontarnos posiblemente a días previos al recorte temporal señalado.Mesa 23: La guerra como objeto de estudio de las ciencias humanas. Problemas teóricos y abordajes de conflictos concretos, de la antigüedad al presenteFacultad de Humanidades y Ciencias de la Educació

Automation of three-dimensional structured mesh generation for turbomachinery blade passages

Hybrid tools have been developed which greatly reduce the time required to generate three-dimensional structured CFD meshes for turbomachinery blade passages. RAGGS, an existing Rockwell proprietary, general purpose mesh generation and visualization system, provides the starting point and framework for tool development. Utilities which manipulate and interface with RAGGS tools have been developed to (1) facilitate blade geometry inputs from point or CAD representations, (2) automate auxiliary surface creation, and (3) streamline and automate edge, surface, and subsequent volume mesh generation from minimal inputs. The emphasis of this approach has been to maintain all the functionality of the general purpose mesh generator while simultaneously eliminating the bulk of the repetitive and tediuos manual steps in the mesh generation process. Using this approach, mesh generation cycle times have been reduced from the order of days down to the order of hours

Evaluation of SMAP Freeze/Thaw Retrieval Accuracy at Core Validation Sites in the Contiguous United States

Seasonal freeze-thaw (FT) impacts much of the northern hemisphere and is an important control on its water, energy, and carbon cycle. Although FT in natural environments extends south of 45°N, FT studies using the L-band have so far been restricted to boreal or greater latitudes. This study addresses this gap by applying a seasonal threshold algorithm to Soil Moisture Active Passive (SMAP) data (L3_SM_P) to obtain a FT product south of 45°N (‘SMAP FT’), which is then evaluated at SMAP core validation sites (CVS) located in the contiguous United States (CONUS). SMAP landscape FT retrievals are usually in good agreement with 0–5 cm soil temperature at SMAP grids containing CVS stations (\u3e70%). The accuracy could be further improved by taking into account specific overpass time (PM), the grid-specific seasonal scaling factor, the data aggregation method, and the sampling error. Annual SMAP FT extent maps compared to modeled soil temperatures derived from the Goddard Earth Observing System Model Version 5 (GEOS-5) show that seasonal FT in CONUS extends to latitudes of about 35–40°N, and that FT varies substantially in space and by year. In general, spatial and temporal trends between SMAP and modeled FT were similar