Showing papers on "Secondary circulation published in 2005"

Diagnosed Three-Dimensional Axisymmetric Structure of the Mulhall Tornado on 3 May 1999

Abstract: On 3 May 1999, an unusually large tornado that caused F4-level damage and killed several people was intercepted by the Doppler on Wheels (DOW) mobile radar near Mulhall, Oklahoma, from a range of 4 to 9 km, resulting in high-resolution volumetric data every 55 s up to 1.5-km altitude over a period of 14 min. For the first time, the evolution and three-dimensional structure of a tornado were deduced using the ground-based velocity track display (GBVTD) technique. After the circulation center was determined, the tangential wind and radial wind were derived from the GBVTD technique at each radius and height. In addition, the axisymmetric vertical velocity, angular momentum, vorticity, and perturbation pressure were deduced from the tangential and radial wind fields. This study focuses on the axisymmetric aspects of this tornado. The primary circulation of the Mulhall tornado consisted of an 84 m s 1 peak axisymmetric tangential wind with the radius of maximum wind (RMW) ranging from 500 to 1000 m. The secondary circulation exhibited a two-cell structure characterized by a central downdraft surrounded by an annular updraft near the RMW. The calculated maximum pressure deficit from a 3-km radius to the tornado center at 50-m altitude was 80 hPa. The maximum vorticity during the first 8 min of observation was located inside the RMW away from the tornado center. This vorticity profile satisfied the necessary condition of barotropic instability. As the tornado weakened afterward, the vorticity monotonically increased toward the center. The computed swirl ratios were between 2 and 6, consistent with the observed multiple vortex radar signatures and the vorticity pattern. Swirl ratios were generally smaller during the weakening phase.

Behavior of Meandering Overbank Channels with Graded Sand Beds

Abstract: Measurements of velocity distributions, depth variation, and sediment transport have been made under bankfull and overbank flow conditions in meandering channels with a graded sand bed, using the large-scale U.K. Flood Channel Facility. The overbank conditions depend upon the relative strength of opposing secondary circulation cells generated by shear at the channel crossover and centrifugal forces around the meander bend. Generally the shear-generated secondary flow either reversed or weakened the centrifugal circulation around the next downstream bend. This led to considerable modification of the main channel bed morphology, which, in turn, altered flow distributions. Measurements of the lateral distribution of bed load were made using a -scale Helley.Smith sampler. This demonstrated that the bed load was generally concentrated within a limited width of the channel and tended to take the shortest route through the meanders. Comparisons of observed and calculated bed material load gives an indication of how secondary circulation around meanders, under both bankfull and overbank conditions, affects the predictive performance of formulas derived for predominantly one-dimensional flow.

Shear-forced vertical circulations in tropical cyclones

Abstract: [1] The forced secondary circulation (FSC) by the vertical shear of horizontal winds is isolated from the latent heating and friction FSCs associated with a model-simulated hurricane vortex. This is achieved by use of a newly developed potential vorticity inversion and quasi-balanced vertical motion equations system. Results show that latent heating forces intense updrafts in the eyewall and slow subsidence in the eye, whereas the friction-FSC is similar to that of the Ekman pumping, with the peak ascent occurring near the top of the boundary layer in the eye. In contrast, when an environmental westerly shear is superposed with an axisymmetric balanced vortex, an anticlockwise FSC appears across the inner-core region with the rising motion downshear and easterly sheared horizontal flows in the vertical. The resulting horizontal flows act to reduce the influence of the vertical shear inside the storm by as much as 30–40%, thus opposing the destructive roles of the vertical shear.

The Influence of Uniform Flow on Tropical Cyclone Intensity Change

Abstract: The influence of a uniform flow on the structural changes of a tropical cyclone (TC) is investigated using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) Idealized experiments are performed on either an f plane or a β plane A strong uniform flow on an f plane results in a weaker vortex due to the development of a vertical wind shear induced by the asymmetric vertical motion and a rotation of upper-level anticyclone The asymmetric vertical motion also reduces the secondary circulation of the vortex On a β plane with no flow, a broad anticyclonic flow is found to the southeast of the vortex, which expands with time Similar to the f-plane case, asymmetric vertical motion and vertical wind shear are also found This beta-induced shear weakens the no-flow case significantly relative to that on an f plane When a uniform flow is imposed on a β plane, an easterly flow produces a stronger asymmetry whereas a westerly flow reduces it

Finite volume modeling of variable density shallow-water flow equations for a well-mixed estuary : application to the Río Maipo estuary in central Chile

Abstract: Strong advective flows in well-mixed estuaries can produce abrupt fronts and density gradients, which cause secondary circulation and affect the ecosystem by generating recirculation or accumulation of pollutants inside the estuary. To model these complex phenomena, a method capable of adequately representing the dynamics of the flow by considering the salt as an active tracer, influencing the transport within the estuary, is required. A numerical model based on the finite volume MUSCL-Hancock method is used to solve the shallow-water flow equations in combination with an advection/diffusion of salt equation, to simulate two-dimensional unsteady flow in a vertically well-mixed estuary. The salt transport equation is coupled to the momentum equations via the hydrostatic term, which permits simulation of baroclinic secondary circulation. A series of benchmark test problems are used to validate the model and demonstrate its capabilities. The model is then used to simulate the saline intrusion within the Rib ...

Fluid circulation apparatus for temporary heating

Abstract: A temporary heating apparatus comprises a portable heat exchanger which transfers heat from a hot fluid circulating in a primary circulation loop thereof to a heated liquid circulating in a secondary circulation loop thereof. The heat exchanger is connectable to a hot fluid source such that hot fluid from the hot fluid source circulates through the primary circulation loop. A portable remote heating unit comprises a fluid coil releasably connected by flexible conduits to the secondary circulation loop, and a secondary pump is connected to the flexible conduits and the secondary circulation loop to pump heated liquid through the secondary circulation loop, flexible conduits, and the fluid coil of the remote heating unit. The heat exchanger isolates the heating circuit from the hot fluid source, allowing the use of steam as the hot fluid source, and further allowing high pressures in the heating circuit, such as encountered in tall buildings.

Secondary circulation cooling system

Abstract: To provide a secondary circulation cooling system using a composition which is less influential over the environment as a secondary coolant, is non-inflammable, has a small pressure drop particularly at a low temperature and has a large heat transfer coefficient. A secondary circulation cooling system comprising a primary cooling means 1 using a primary coolant, a secondary circulation cooling means 13 using a secondary coolant and a heat exchange means 6 to carry out heat exchange between the primary coolant and the secondary coolant, characterized in that a composition comprising a fluorinated ether such as CF 2 HCF 2 OCH 2 CF 3 , and an alcohol such as ethanol, is used as the secondary coolant.

Two dimensional ageostrophic secondary circulation at ocean fronts due to vertical mixing and large scale deformation

Abstract: [1] Ageostrophic secondary circulation (ASC) in frontal data sets have been previously diagnosed using only adiabatic versions of Omega equations. This study includes the effect of vertical mixing on such diagnostics. Modified quasi-geostrophic and semigeostrophic balance equations are examined for the existing Azores front data sets and idealized fronts in the presence of diabatic vertical mixing as well as a large-scale deformation field. The relevant dimensionless parameter representing the relative importance of large-scale deformation and vertical mixing is the inverse of the Ekman number based on the deformation rate (αH2/Ao), where α is large-scale deformation rate, H is vertical scale of the front, and Ao is the maximum vertical eddy viscosity; when this parameter is smaller than O(102), the influence of vertical mixing may be important. Other relevant parameters include Burger number, Bu, and Prandtl number, Pr. The vertical velocity in ASCs caused by diabatic mixing in all diagnostics solutions except for large Bu cases shows good agreement with the Garrett-Loder scaling. The structure of ASCs is found to be sensitive to Pr. The diagnostics of ASCs for the Azores front data set indicates that the vertical mixing intensifies the ASC in the upper ocean (∼100 m) and should not be neglected, when the large-scale deformation rate, α, is O(10−6 s−1) or smaller. The magnitude of vertical velocity in ASCs due to mixing contributions reaches ∼O(10 m d−1) with downwelling on the dense side and upwelling on the less dense side of Azores front.

Device for carrying out thermal circulating process comprises using working substance having temperature in primary circulation which is higher than temperature of working substance in secondary circulation

Abstract: A device for carrying out a thermal circulating process comprises using a working substance having a temperature in the primary circulation (1) after releasing the pressure in the pressure releasing unit (6) which is higher than the temperature of the working substance in the secondary circulation (2) after compressing in a compressor (9) The working substance in the secondary circulation is heated and evaporated by the heat of condensation of the working substance in the primary circulation The working substance partially contains water in the secondary circulation An independent claim is also included for a thermal circulating process

Secondary circulation within a tropical cyclone observed with L-band wind profilers

Abstract: . In association with the passage of a Tropical Cyclone (TC) around Japan, the secondary circulation in the region from the outer side to the center was investigated in detail by two separately located L-band wind profilers and the rawinsonde observations from 1 to 2 October 2002, for the first time. As the wind profilers can observe wind fields not only within rainbands but also in between, the mesoscale wind circulation including the vertical wind component in wide areas from the lower layer to the upper layer was investigated. While the TC center approached the profiler stations, several rainbands associated with the TC subsequently passed. Relatively warm, moist inflow with a cyclonic rotation was observed in the lower-troposphere while the TC center approached. The inflow reached the inside of the main rainband where the updraft was observed. Above 5-km height (with temperature below 0°C), outflow and weak downdraft corresponding to falling frozen particles were observed. It is considered that the frozen particles formed precipitating clouds mainly in the outer rainband region. The continuous wind circulation transported water vapor from the lower troposphere to the upper troposphere via the vicinity of TC center. On the other hand, after the passage of the TC center, the developed rainband passed, which was located in the south and southwest quadrant of the TC. It is suggested with the profilers' data that the rainband was intensified mainly by warm and moist outflow below 3-km height.

Air temperature control apparatus in room

Abstract: FIELD: automatic control systems, namely controlling air temperature in rooms heated by means of open heat supply systems. ^ SUBSTANCE: apparatus is designed for controlling air temperature in room heated by means of open heat supply system having circuits of common and secondary circulation with direct and reverse main lines. Each circuit includes circulation pump with drive unit and revolution number regulator. Main line of pump of secondary circulation circuit is connected with outlet of pressure controller and main line of pump of common circulation circuit is connected with outlet of air temperature controller. Apparatus also includes pickup for detecting temperature of reverse heat transfer agent at outlet of heating system. Heat quantity meter is mounted at outlet of circulation pump of direct main line of common circulation. Flow rate meter of heat transfer agent is mounted at outlet of circulation pump of secondary circulation circuit. ^ EFFECT: enhanced effectiveness of apparatus, lowered flow rate of heat transfer agent of common circulation circuit at maximum use of energy potential of heat transfer agent and increased flow rate of heat transfer agent of additional circulation circuit, optimal heat consumption and electric energy cost in drive units of pumps. ^ 1 cl, 1 dwg

Advertisement circulation analyzing system, advertisement circulation analysis method, advertisement circulation analysis program and advertisement circulation analyzing apparatus

Abstract: PROBLEM TO BE SOLVED: To provide an advertisement circulation analyzing system, an advertisement circulation analysis method, an advertisement circulation analysis program and an advertisement circulation analyzing device for efficiently carrying out circulation analysis, such as acquisition of the overall advertisement effects, including secondary circulation, the specifying of the factor for the increase in the circulation effects and the specifying of the factor of the hinderance of the circulation effects. SOLUTION: In this advertisement circulation analyzing system, using an advertisement circulation analytic model expressing the respective states of a circulation process that includes primary circulation and secondary circulation and inter-state transitional probability, the measurement data acquiring part of an analyzing apparatus acquires circulation information, measured by a measurement device on a network, and a transition probability calculating part calculates the transition probability in each sample time, based on the circulation information, and a transition state calculating part calculates the evaluation value of the transitional status in the latest sampling time from the transition probability in the latest sample time and the transition state immediately prior to the sample time, and stores the calculated latest evaluation value into a transition state storing part. Furthermore, an analysis processing part analyzes the circulating state of advertisement, based on the transition information stored in the transition state storing part. COPYRIGHT: (C)2006,JPO&NCIPI

Application of Q-Vector Theory to “02.6” Heavy Storm Rain on the East Side of Qinghai-Xizang Plateau

Abstract: By using the routine sounding and surface observation data, the circulation features and physical causes for the heavy storm rain process occurred in Shaanxi on the east side of Qinghai-Xizang Plateau on 8~9 June 2002 were diagnosed and analyzed. Furthermore, based on MM4 model output production, a mesoscale analysis was made according to %Q%-vector theory. The results show that the distribution of wet %Q%-vector indicates the direction and intensity of the secondary circulation. The heavy storm rain may occur when the mesoscale circulation enhanced. The partition of wet Q-vector indicates mesoscale feature in the heavy storm rain.