Search results for " Kinetic energy"
showing 10 items of 46 documents
A dynamic subgrid-scale tensorial eddy viscosity model
1999
In the Navier-Stokes equations the removal of the turbulent fluctuating velocities with a frequency above a certain fixed threshold, employed in the Large Eddy Simulation (LES), causes the appearance of a turbulent stress tensor that requires a number of closure assumptions. In this paper insufficiencies are demonstrated for those closure models which are based on a scalar eddy viscosity coefficient. A new model, based on a tensorial eddy viscosity, is therefore proposed; it employs the Germano identity [1] and allows dynamical evaluation of the single required input coefficient. The tensorial expression for the eddy viscosity is deduced by removing the widely used scalar assumption of the …
Analysing longitudinal turbulence intensity in vegetated channels
2007
Vegetation altering hydrodynamic conditions of an open channel flow controls the exchanges of sediment, nutrients and contaminants. In this paper the turbulence structure of open-channel flow over a flexible grass vegetation is investigated. Velocity measurements were carried out, in a rectangular flume, using a 2D-ADV (Acoustic Doppler Velocimeter) for different values of stem concentration, water discharge, and bed slope. The experimental results showed that: 1) the maximum value of the longitudinal turbulence intensity occurs at a water depth close to the bent vegetation height; 2) the turbulence intensity damps for increasing values of the stem concentration; 3) above the vegetation hei…
Mesonic exchange current contribution to K+ nucleus scattering.
1993
A microscopical many-body calculation of the self-energy of a positive kaon interacting with a nucleus is carried out of kinetic energies Tk up to 500MeV. On top of the well know contribution of the impulse approximation, we have considered the kaon coupling to the pions in the nucleus. Previous approximations for the pionic cloud contribution, specially on the imaginary part from the pionic cloud wich were not previously considered. The results for the total and differential cross sections are satisfactory after these new contributions are included, but uncertainties remain in the real part. Nieves Pamplona, Juan Miguel, Juan.M.Nieves@ific.uv.es ; Oset Baguena, Eulogio, Eulogio.Oset@ific.u…
Analysis of wave energy conversion process
2011
Since wave energy conversion technologies are developing due to the depletion of fossil fuels and due to their hazardous effects on the environment, an important and unexploited source of energy is wave energy. The paper proposes to compare theoretical data obtained using specialized software and data obtained via laboratory measurements using a scale model, regarding the mechanical torque generated at the axis of the electric motor. The data collected represent the kinetic and potential energy, simulating Black Sea waves using an installation proposed to be patented, an installation that converts off-shore wave energy.
Analysis of the energy balance closure over a FLUXNET boreal forest in Finland
2010
Abstract. The imbalance in the surface energy budget, when using eddy-covariance techniques to measure turbulent fluxes, is still an unresolved problem. Important progresses have been reported in recent years identifying potential reasons for this lack of energy balance closure. In this paper we focus on the data collected in a FLUXNET boreal forest site in Sodankylä, Finland. Using one month half-hourly data, an average Energy Balance Ratio (EBR) of 0.72 is obtained. The inclusion of the heat storage terms in the energy budget yields an improvement of about 6% in the total closure. The sensitivity of the energy balance closure to the turbulence intensity is analysed in terms of the frictio…
Dynamics of supercooled confined water measured by deep inelastic neutron scattering
2017
In this paper, we present the results of deep inelastic neutron scattering (DINS) measurements on supercooled water confined within the pores (average pore diameter ~ 20 Ã ) of a disordered hydrophilic silica matrix obtained through hydrolysis and polycondensation of the alkoxide precursor Tetra-Methyl-Ortho-Silicate via the sol-gel method. Experiments were performed at two temperatures (250 K and 210 K, i.e., before and after the putative liquidâliquid transition of supercooled confined water) on a âwetâ sample with hydration h ~ 40% w/w, which is high enough to have water-filled pores but low enough to avoid water crystallization. A virtually âdryâ sample at h ~ 7% was also inve…
"Figure 9c-2" of "Deviation from quark-number scaling of the anisotropy parameter v_2 of pions, kaons, and protons in Au+Au collisions at sqrt(s_NN) …
2023
The quark-number-scaled $v_2$ ($v_2/n_q$) of identified hadrons are shown as a function of the kinetic energy per quark, KE$_T/n_q$ in 0–10% centrality [panel (a)] in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The error bars (shaded boxes) represent the statistical (systematic) uncertainties. The systematic uncertainties shown are type A and B only.
"Figure 8b-2" of "Deviation from quark-number scaling of the anisotropy parameter v_2 of pions, kaons, and protons in Au+Au collisions at sqrt(s_NN) …
2023
Identified hadron $v_2$ in central (0–20% centrality, left panels) Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Panels (a) and (b) show $v_2$ as a function of transverse momentum $p_T$. The $v_2$ of all species for centrality 0–20% has been scaled up by a factor of 1.6 for better comparison with results of 20–60% centrality. The error bars (shaded boxes) represent the statistical (systematic) uncertainties. The systematic uncertainties shown are type A and B only.
"Figure 10b-2" of "Deviation from quark-number scaling of the anisotropy parameter v_2 of pions, kaons, and protons in Au+Au collisions at sqrt(s_NN)…
2023
The quark-number-scaled $v_2$ ($v_2/n_q$) of identified hadrons are shown as a function of the kinetic energy per quark, KE$_T/n_q$ in 10–40% centrality [panel (b)] in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The $v_2$ of $\Lambda$ and K$^0_S$ are measured by STAR collaboration [21]. The error bars (open boxes) represent the statistical (systematic) uncertainties. The systematic uncertainties shown on the results from this study are type A and B only.
"Figure 10b-1" of "Deviation from quark-number scaling of the anisotropy parameter v_2 of pions, kaons, and protons in Au+Au collisions at sqrt(s_NN)…
2023
The quark-number-scaled $v_2$ ($v_2/n_q$) of identified hadrons are shown as a function of the kinetic energy per quark, KE$_T/n_q$ in 10–40% centrality [panel (b)] in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The $v_2$ of $\Lambda$ and K$^0_S$ are measured by STAR collaboration [21]. The error bars (open boxes) represent the statistical (systematic) uncertainties. The systematic uncertainties shown on the results from this study are type A and B only.