378 research outputs found
Buoyancy-assisted mixed convection flow over a heated square cylinder in a vertical channel
Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.This paper investigates numerically the flow and heat transfer in air (Pr=0.71) by mixed convection past a heated square cylinder under aiding buoyancy effect in a confined channel. The numerical simulations are performed in the range of parameters 20≤Re≤45 and 1.61x103 ≤Gr≤6.33x103for a fixed blockage ratio D/L of 0.1. The combination in the present study of these two Re and Gr parameters is reduced so that the Richarson number varies from 0,8 to 8, in order to neglect neither free convection (Ri10). The steady two-dimensional governing equations are solved by the finite volume formulation using the open source OpenFoam® code. The representative flow structure, isotherm patterns and local Nusselt number evolution are presented and discussed. The effect of both the Reynolds number and the buoyancy parameter on the fluid flow and the heat transfer are also analyzed. It is found that the wake region size strongly depends on both Reynolds and Grashof numbers and this region is shown to increase in size increasing the Reynolds number and/or decreasing the Grashof number. Moreover, increasing the Reynolds number leads to a heat transfer enhancement more pronounced on the front face of the obstacle, whereas increasing the Grashof number leads to a heat transfer enhancement more pronounced on the side faces.dc201
Co-existing structures in 105Ru
New positive-parity states, having a band-like structure, were observed in
105Ru. The nucleus was produced in induced fission reaction and the prompt
gamma-rays, emitted from the fragments, were detected by the EUROBALL III
multi-detector array. The partial scheme of excited 105Ru levels is analyzed
within the Triaxial-Rotor-plus-Particle approach
High-spin rotational bands in 123 I
High-spin states in 123I were populated in the reaction 80Se(48Ca,p4n)123I at a beam energy of 207 MeV and Îł-ray coincidence events were measured using the Gammasphere spectrometer. Three weakly populated, high-spin rotational bands have been discovere
Mixed Representation RPA Calculation for Octupole Excitations on Superdeformed Sates in the 40Ca and Neutron-Rich Sulfur Regions
By means of the mixed representation RPA based on the Skyrme-Hartree-Fock
mean field, we investigate low-frequency octupole excitations built on the
superdeformed (SD) states in the N=Z nuclei around 40Ca and the neutron-rich
Sulfur isotopes. The RPA calculation is carried out fully self-consistently on
the three-dimensional Cartesian mesh in a box, and yields a number of
low-frequency octupole vibrations built on the SD states in 32S, 36Ar, 40Ca and
44Ti. In particular, a strongly collective K^\pi=1^- octupole vibration is
suggested to appear on top of the SD state in 40Ca. For 48,50S close to the
neutron drip line, we find that the low-lying state created by the excitation
of a single neutron from a loosely bound low Omega level to a high Omega
resonance level acquires an extremely strong octupole transition strength due
to the spatially very extended structure of the particle-hole wave functions.Comment: 22 pages, 7 figure
Relative spins and excitation energies of superdeformed bands in 190Hg: Further evidence for octupole vibration
An experiment using the Eurogam Phase II gamma-ray spectrometer confirms the
existence of an excited superdeformed (SD) band in 190Hg and its very unusual
decay into the lowest SD band over 3-4 transitions. The energies and dipole
character of the transitions linking the two SD bands have been firmly
established. Comparisons with RPA calculations indicate that the excited SD
band can be interpreted as an octupole-vibrational structure.Comment: 12 pages, latex, 4 figures available via WWW at
http://www.phy.anl.gov/bgo/bc/hg190_nucl_ex.htm
Revised level structure of 120Te
The level scheme of the nucleus Te120, populated in the reaction Se80(Ca48,α4n), was reinvestigated using γ-ray coincidence data measured with the Gammasphere spectrometer. Previously, five high-spin rotational bands were discovered in this nucleus. Th
Observation of Positive-Parity Bands in Pd and Pd: Enhanced -Softness
The neutron-rich nuclei Pd and Pd were produced as fission
fragments following the Si + Er reaction at 142 MeV. Using the
identification based on the coincidences with the complementary fission
fragments, the only positive-parity bands observed so far in Pd and
Pd emerged from this work. A band, built on top of the 5/2 ground
state exhibiting = 1 energy-level staggering, was observed in each
of these nuclei. Both nuclei of interest, Pd and Pd, are
suggested to lie in the transitional region of Pd isotopes of maximum
-softness. The ground states of both nuclei are predicted by TRS
calculations to be extremely -soft with shallow triaxial minima. The
first crossing in the new bands is proposed to be due to an alignment of
neutrons
Collective and noncollective states in (120)Te
High-spin states in (120)Te were populated in the reaction (80)Se((48)Ca, alpha 4n)(120)Te at a beam energy of 207 MeV and gamma-ray coincidences were measured using the Gammasphere spectrometer. The previously known level scheme is extended to higher spin and new interband transitions and side-feeding branches are established. Five highly deformed rotational bands, extending up to almost I = 50, are observed for the first time. The bands are compared with similar structures found recently in neighboring nuclei. The experimental results are interpreted within the framework of the cranked Nilsson-Strutinsky model. Configuration assignments to several terminating states and to the high-spin bands are discussed
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