Large eddy simulation of turbulent flow in Rayleigh-Benard configuration

This work undertakes a numerical study of turbulent incompressible flows in Rayleigh-Benard configurations using Large Eddy Simulation and two sub-grid scale models, i.e., the WALE (Wall Adapting Local Eddy-viscosity) model and the corresponding dynamic sub-grid model (DSGS). In the process of using DSGS, an optimal value of constant  of the WALE model was determined for the envisaged Rayleigh number (Ra=6.3.105). The computed numerical results (on a relatively coarse grid) showed good agreement with those Direct Numerical Simulation (DNS) results found in the literature. It is observed that the profiles obtained are highly dependent on the time interval over which the statistics are made (equivalent to the Interval of Statistical Analysis (ISA)). Keywords -Turbulent natural convection, Finite volume method, Large eddy simulation

Content Analysis of the United States' Television Network Coverage of the Three Worlds: A Survey of Themes June 11, 1983 to January 1, 1988

Higher Educatio

3-D Seismic Interpretation and Volumetric Estimation of “Osaja Field” Niger Delta, Nigeria

3-D seismic interpretation and petrophysical analysis of the Osaja Field, Niger Delta, was carried out with aim of carrying out a detailed structural interpretation, reservoir characterization and volumetric estimation of the field. Four wells were correlated across the field to delineate the lithology and establish the continuity of reservoir sand as well as the general stratigraphy of the area. The petrophysical analysis carried out, revealed two sand units that are hydrocarbon bearing reservoirs (Sand_A and Sand_B).The spatial variation of the reservoirs were studied on a field wide scale using seismic interpretation. Time and depth structural maps generated were used to establish the structural architecture/geometry of the prospect area of the field. The depth structure map revealed NE-SW trending anticlinal structures with F5 and F6 as faults assisted closures to the reservoir. Furthermore, reservoir parameters such as net pay, water saturation porosity, net-to-gross etc, were derived from the integration of seismic and well log data. The structural interpretation on the 3-D seismic data of the study area revealed a total of seven faults ranging from synthetic to antithetic faults. The petrophysical analysis gave the porosity values of the reservoir Sand_A ranging from 18.1 - 20.3% and reservoir Sand_B ranging from 13.1-14.9% across the reservoir. The permeability values of reservoir Sand_A ranging from 63-540md and reservoir Sand_B ranging from 18-80md hence there is decrease in porosity and permeability of the field with depth.The net-to-gross varies from 22.1% to 22.4% in Rerservoir Sand A to between 5.34- 12% for Rerservoir Sand _A while Sw values for the reservoirs ranges from 38-42% in well 2 to about 68.79-96.06% in well 11. The result of original oil in place for all the wells calculated revealed that well 2 has the highest value with 9.3mmbls. These results indicate that the reservoirs under consideration have a poor to fair hydrocarbon (oil) prospect

Investigation Of Temperature Dependent Characteristics Of Compound TbCo2 Using Neutron Powder Diffraction Technique

The structure, magnetization and magnetostriction of Laves phase compound TbCo2 were investigated by temperature dependent high resolution neutron powder diffraction. The compound crystallizes in the cubic Laves phase C15 structure above its Curie temperature, TC and exhibits a rhombohedral distortion (space group R3m) below TC. By an appropriate extrapolation of the temperature factor of Co atom above TC, the Rietveld refinement of the neutron powder diffraction data of the rhombohedral structure converges satisfactorily and reveals that the moments of Co1 (3b) and Co2 (9e) are almost equal. The moment follows well the Brillouin function. The total magnetic moment of TbCo2 was found to be 5.8μB/ f.u; the anisotropic magnetostriction constant &#955III is about 4.6 x 10-3 and the volume magnetostriction ωs is about 8.7 x 10-3 at 14K. Keywords: Magnetic structure; neutron powder diffraction; laves phase; rhombohedral distortion. Nigerian Journal of Physics Vol. 19 (1) 2007: pp. 31-3