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This paper presents the performance comparison of various parallel lattice Boltzmann codes for simulation of incompressible laminar convection in 2D and 3D channels. Five different parallel libraries namely; matlabpool, pMatlab, GPU-Matlab, OpenMP and OpenMP+OpenMPI were used to parallelize the serial lattice Boltzmann method code. Domain decomposition method was adopted for parallelism for 2D and 3D uniform lattice grids. Bhatnagar-Gross-Krook approximation with lattice types D2Q9, D2Q19 and D2Q5, D2Q6 were considered to solve 2D and 3D fluid flow and heat transfer respectively. Parallel computations were conducted on a workstation and an IBM HPC cluster with 32 nodes. Laminar forced convection in a 2D and turbulent forced convection in a 3D channels was considered as a test case. The performance of parallel LBM codes was compared with serial LBM code. Results show that for a given problem, parallel simulations using matlabpool and pMatlab library perform almost equal. Parallel simulations using C language with OpenMP libraries were 10 times faster than simulations involving Matlab parallel libraries. Parallel simulations with OpenMP+OpenMPI were 0.35 times faster than the reported parallel lattice Boltzmann method code in the literature. [ABSTRACT FROM AUTHOR]

This paper presents a numerical modeling and simulation of incompressible laminar mixed convection in rotating channels using parallel lattice Boltzmann method. Individual distribution functions with D3Q19 and D3Q6 lattice types were considered to solve fluid flow and heat transfer problems, respectively. The Reynolds number was set to 100, and wall-to-inlet fluid density ratio was set to 0.2. Two rotation modes namely orthogonal and parallel modes were considered with rotation number equal to 0.2. LBM code was written in C language and was parallelized using OpenMP libraries. Domain decomposition method of data parallelism was adopted here, and simulations were conducted on a workstation with dual processors and 64 GB RAM. Predicted velocity and temperature fields were found to agree well with velocity and temperature obtained from Fluent. [ABSTRACT FROM AUTHOR]

A numerical study of incompressible laminar mixed convection in the entrance region of 2-D vertical and inclined channels using the regularized lattice Boltzmann method is presented. Individual distribution functions with lattice types D2Q9 and D2Q5 are considered to solve fluid flow and thermal fields, respectively. Reynolds number is held constant at 100 and Grashof number is varied from 103to 106. The channel inclination angle is varied from 0 to 60°. The aspect ratio of channel is equal to 5. Predicted velocity and temperature fields are in good agreement with velocity and temperature fields found from the finite volume code Fluent. [ABSTRACT FROM PUBLISHER]

A computational study to assess the performance of different gas turbine power plant configurations is presented in this paper. The work includes the effect of humidity, ambient inlet air temperature and types of fuels on gas turbine plant configurations with and without fogger unit. Investigation also covers economic analysis and effect of fuels on emissions. Gas turbine frames of various sizes/ratings are being used in gas turbine power plants in Saudi Arabia. 20MWe GE 5271RA, 40MWe GE-6561B, and 70 MWe GE-6101FA frames are selected for the present study. Fogger units with maximum mass flow rate of 2 kg/s are considered for the present analysis. Reverse osmosis unit of capacity 4 kg/s supplies required water to the fogger units. The relative humidity and temperature have been varied from 30 to 45% and from 80 to 100 °F, respectively. Fuels considered in the study are natural gas, diesel and heavy bunker oil. Simulated gas turbine plant output from Gas turbine PRO has been validated against an existing gas turbine plant output. It has been observed that the simulated plant output is less than the existing gas turbine plant output by 5%. Variation of humidity does not affect the gas turbine performance appreciably for all types of fuels. For a decrease of inlet air temperature by 10 °F, net plant output and efficiency have been found to increase by 5 and 2%, respectively, for all fuels, for gas turbine only situation. However, for gas turbine with fogger scenario, for a decrease of inlet air temperature by 10 °F, net plant output and efficiency have been found to further increase by 3.2 and 1.2%, respectively for all fuels. For all Gas turbine frames with fogger, the net plant output and efficiency are relatively higher as compared to gas turbine only case for all fuels. Net plant output and efficiency for natural gas are higher as compare to other fuels for all gas turbine scenarios. For a given 70MWe frame with and without fogger, break even fuel price and electricity price have been found to vary from 2.2 to 2.5 USD/MMBTU and from 0.020 to 0.0239 USD/kWh, respectively. Turbines operating on natural gas emit less carbon relatively as compared to other fuels. [ABSTRACT FROM AUTHOR]

Electronic structure calculations have the potential to predict key matter transformations for applications of strategic technological importance, from drug discovery to material science and catalysis. However, a predictive physicochemical characterization of these processes often requires accurate quantum chemical modeling of complex molecular systems with hundreds to thousands of atoms. Due to the computationally demanding nature of electronic structure calculations and the complexity of modern high-performance computing hardware, quantum chemistry software has historically failed to operate at such large molecular scales with accuracy and speed that are useful in practice. In this paper, novel algorithms and software are presented that enable extreme-scale quantum chemistry capabilities with particular emphasis on exascale calculations. This includes the development and application of the multi-Graphics Processing Unit (GPU) library LibCChem 2.0 as part of the General Atomic and Molecular Electronic Structure System package and of the standalone Extreme-scale Electronic Structure System (EXESS), designed from the ground up for scaling on thousands of GPUs to perform high-performance accurate quantum chemistry calculations at unprecedented speed and molecular scales. Among various results, we report that the EXESS implementation enables Hartree–Fock/cc-pVDZ plus RI-MP2/cc-pVDZ/cc-pVDZ-RIFIT calculations on an ionic liquid system with 623 016 electrons and 146 592 atoms in less than 45 min using 27 600 GPUs on the Summit supercomputer with a 94.6% parallel efficiency. [ABSTRACT FROM AUTHOR]

The performances of the venturi meters for oil-water flow under real oil well operating conditions were investigated in the present experimental investigation. The pressure drop measurements were studied in Tercom flanged machined venturi meters with a beta ratio (β)=0.4, 0.5 and 0.6 for oil-water two-phase flow experiments in a 0.0762 m (3-in.) pipe. The experimental data for different fluid mixture flow rates and water cuts were acquired using a two-phase, large-scale inclinable flow loop. Potable water and Exxsol mineral oil (D80) were used for the single-phase and two-phase oil-water experiments for the three venturi meters. The experiments were conducted for water cuts varying from 0 to 100% in steps of 20%, flow rates ranging from 2000 to 10,000 barrels per day (bpd), and for horizontal and vertical flow loop inclinations (0∘ and 90∘). Real oil wells flow rates were matched by selecting test liquid flow rates. The experimental results showed that the venturi pressure drop varies as the square of the fluid flow rate for given water cut through the venturi meters studied. For given flow rate and water cut, the venturi pressure drop is inversely proportional to the venturi β; however, the venturi pressure drop varies almost linearly with the water cut for a given fluid flow rate. Within the range of test fluid flow rates, the venturi pressure drop measurements were unaffected by the inclination of the three venturi meters studied in the flow loop. This is very important from an application standpoint. [ABSTRACT FROM AUTHOR]

This study presents an experimental investigation of pressure drop measurements in a Tercom flanged machined venturi meter of 0.5 beta ratio for oil-water two-phase flow in a 0.0762 m (3-in.) pipe. Two-phase large scale inclinable flow loop was used to acquire data for different water cuts and fluid mixture flow rates. Mineral oil D80 and portable water were used for the single phase and two-phase oil-water experiments. The experiments were conducted for flow rates ranging from 2000 to 12000 bpd, water cuts varying from 0% to 100% in steps of 20%, for four flow loop inclinations (0, 40, 60, and 90 degrees) from horizontal to vertical positions. The range of liquid flow rates were selected to match the actual flow rates in real oil wells to reflect field conditions. The results show that the venturi pressure drop varies parabolically with fluid flow rate for given water cut. However, the venturi pressure drop varies linearly with water cut for given fluid flow rate. The corresponding slopes increase slightly with flow rates. The flow loop inclination has no effect on the venturi pressure drop measurements at the considered flow conditions. A new modified venturi coefficient, k, which is a function of pressure losses and geometry, was defined and its value obtained from the oil-water two-phase flow experiments. The mixture venturi pressure coefficient was also defined and determined, and the average value found to be around 15.5 for all flow loop inclinations. The results indicate that the venturi pressure drop and the determined venturi coefficients are unaffected by the flow loop inclination for selected oil-water two-phase flow conditions. In this paper, attention was focused on the variables affecting the performance of the venturi meter for oil-water flow under real oil well operating conditions. [ABSTRACT FROM AUTHOR]