The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Mark Muetzelfeldt - One of the best experts on this subject based on the ideXlab platform.
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Pressure Drag for Shallow Cumulus Clouds: From Thermals to the Cloud Ensemble
Geophysical Research Letters, 2020Co-Authors: Robert S. Plant, Christopher E. Holloway, Mark MuetzelfeldtAbstract:This study takes the first step to bridge the gap between the Pressure Drag of a shallow cloud ensemble and that of an individual cloud composed of rising thermals. It is found that the Pressure Drag for a cloud ensemble is primarily controlled by the dynamical component. The dominance of dynamical Pressure Drag and its increased magnitude with height are independent of cloud lifetime and are common features of individual clouds except that the total Drag of a single cloud over life cycle presents vertical oscillations. These oscillations are associated with successive rising thermals but are further complicated by the evaporation-driven downdrafts outside the cloud. The horizontal vorticity associated with the vortical structure is amplified as the thermals rise to higher altitudes due to continuous baroclinic vorticity generation. This leads to the increased magnitude of local minima of dynamical Pressure perturbation with height and consequently to increased dynamical Pressure Drag.
L I Guojun - One of the best experts on this subject based on the ideXlab platform.
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Transonic flow of moist air around an NACA 0012 airfoil with non-equilibrium condensation
Progress in Natural Science, 2005Co-Authors: Li Liang, Sun Xiuling, Feng Zhen-ping, L I GuojunAbstract:Abstract The classical condensation model of water vapor is coupled with the Euler equation to calculate transonic flows of moist air with non-equilibrium condensation. By means of this model, numerical computations are implemented to investigate the aerodynamic characteristics of an NACA 0012 airfoil in transonic flows of moist air at various angles of attack and relative humidities, and the results are compared with those in dry air flows. For different angle of attack considered at 50% relative humidity, the lift decreases 30%–40%. The Pressure Drag increases when the angle of attack is smaller than 1.4° and decreases when higher than 1.4°. At zero angle of attack, with the relative humidity rising from zero to 90%, the Pressure Drag increases exponentially. At 90% relative humidity, the Pressure Drag increases 160%, and self-oscillation takes place periodically and alternately over the upper and lower surfaces of the airfoil. the oscillation is caused by the interactions of local supersonic flow and h...
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Transonic flow of moist air around an NACA 0012 airfoil with non-equilibrium condensation
Progress in Natural Science, 2005Co-Authors: Li Liang, Sun Xiuling, Feng Zhenping, L I GuojunAbstract:The classical condensation model of water vapor is coupled with the Euler equations to calculate transonic flows of moist air with non-equilibrium condensation. By means of this model, numerical computations are implemented to investigate the aerodynamic characteristics of an NACA 0012 airfoil in transonic flows of moist air at various angles of attack and relative humidities, and the results are compared with those in dry air flows. For different angles of attack considered at 50% relative humidity, the lift decreases 30%—40%. The Pressure Drag increases when the angle of attack is smaller than 1.4° and decreases when higher than 1.4°. At zero angle of attack, with the relative humidity rising from zero to 90%, the Pressure Drag increases exponentially. At 90% relative humidity, the Pressure Drag increases 160%, and self-oscillation takes place periodically and alternately over the upper and lower surfaces of the airfoil. The oscillation is caused by the interactions of local supersonic flow and heat release in the condensation process.
Robert S. Plant - One of the best experts on this subject based on the ideXlab platform.
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Pressure Drag for Shallow Cumulus Clouds: From Thermals to the Cloud Ensemble
Geophysical Research Letters, 2020Co-Authors: Robert S. Plant, Christopher E. Holloway, Mark MuetzelfeldtAbstract:This study takes the first step to bridge the gap between the Pressure Drag of a shallow cloud ensemble and that of an individual cloud composed of rising thermals. It is found that the Pressure Drag for a cloud ensemble is primarily controlled by the dynamical component. The dominance of dynamical Pressure Drag and its increased magnitude with height are independent of cloud lifetime and are common features of individual clouds except that the total Drag of a single cloud over life cycle presents vertical oscillations. These oscillations are associated with successive rising thermals but are further complicated by the evaporation-driven downdrafts outside the cloud. The horizontal vorticity associated with the vortical structure is amplified as the thermals rise to higher altitudes due to continuous baroclinic vorticity generation. This leads to the increased magnitude of local minima of dynamical Pressure perturbation with height and consequently to increased dynamical Pressure Drag.
Peter B. Rhines - One of the best experts on this subject based on the ideXlab platform.
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Greenland’s Pressure Drag and the Atlantic Storm Track
Journal of the Atmospheric Sciences, 2007Co-Authors: Thomas Jung, Peter B. RhinesAbstract:Abstract Some effects of Greenland on the Northern Hemisphere wintertime circulation are discussed. Inviscid Pressure Drag on Greenland’s slopes, calculated from reanalysis data, is related to circulation patterns. Greenland lies north of the core of the tropospheric westerly winds. Yet strong standing waves, which extend well into the stratosphere, produce a trough/ridge system with jet stream lying close to Greenland, mean Icelandic low in its wake, and storm track that interacts strongly with its topography. In the lower troposphere, dynamic height anomalies associated with strongly easterly Pressure Drag on the atmosphere are quite localized in space and relatively short-lived compared to upper levels, yet they involve a hemispheric-scale dislocation of the stratospheric polar vortex. It is a two-scale problem, however; the high-pass time-filtered part of the height field, responsible for 73% of the Pressure Drag, is quite different, and expresses propagating cyclonic development in the Atlantic storm...
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greenland s Pressure Drag and the atlantic storm track
Journal of the Atmospheric Sciences, 2007Co-Authors: Thomas Jung, Peter B. RhinesAbstract:Abstract Some effects of Greenland on the Northern Hemisphere wintertime circulation are discussed. Inviscid Pressure Drag on Greenland’s slopes, calculated from reanalysis data, is related to circulation patterns. Greenland lies north of the core of the tropospheric westerly winds. Yet strong standing waves, which extend well into the stratosphere, produce a trough/ridge system with jet stream lying close to Greenland, mean Icelandic low in its wake, and storm track that interacts strongly with its topography. In the lower troposphere, dynamic height anomalies associated with strongly easterly Pressure Drag on the atmosphere are quite localized in space and relatively short-lived compared to upper levels, yet they involve a hemispheric-scale dislocation of the stratospheric polar vortex. It is a two-scale problem, however; the high-pass time-filtered part of the height field, responsible for 73% of the Pressure Drag, is quite different, and expresses propagating cyclonic development in the Atlantic storm...
Christopher E. Holloway - One of the best experts on this subject based on the ideXlab platform.
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Pressure Drag for Shallow Cumulus Clouds: From Thermals to the Cloud Ensemble
Geophysical Research Letters, 2020Co-Authors: Robert S. Plant, Christopher E. Holloway, Mark MuetzelfeldtAbstract:This study takes the first step to bridge the gap between the Pressure Drag of a shallow cloud ensemble and that of an individual cloud composed of rising thermals. It is found that the Pressure Drag for a cloud ensemble is primarily controlled by the dynamical component. The dominance of dynamical Pressure Drag and its increased magnitude with height are independent of cloud lifetime and are common features of individual clouds except that the total Drag of a single cloud over life cycle presents vertical oscillations. These oscillations are associated with successive rising thermals but are further complicated by the evaporation-driven downdrafts outside the cloud. The horizontal vorticity associated with the vortical structure is amplified as the thermals rise to higher altitudes due to continuous baroclinic vorticity generation. This leads to the increased magnitude of local minima of dynamical Pressure perturbation with height and consequently to increased dynamical Pressure Drag.