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排序方式: 共有154条查询结果,搜索用时 15 毫秒
31.
Hasan Nemati Kurosh Sedighi Mohammad Mohammadi Pirouz Ehsan Fattahi 《International Journal of Computational Fluid Dynamics》2013,27(3-4):83-94
A numerical investigation of the two-dimensional laminar flow around side-by-side rotating circular cylinders using Lattice Boltzmann method is conducted. The effects of variation of rotational speed ratio β and different gap spacings g* at Reynolds number of 100 are studied. A various range of rotational speed ratio 0 ≤ β ≤ 2 for four different gap spacings of 3, 1.5, 0.7 and 0.2 are investigated. Flow conditions and its characteristics, such as lift and drag coefficients and Strouhal number, is studied. The results indicated that as β increases, the flow changes its condition from periodic to steady after a critical rotational speed. Results also indicated that variation of the gap spacing and rotational speed has significant effect on wake pattern. Wake pattern in turn has significant effect on the Strouhal number. Finally, the result is compared with experimental and other numerical data. 相似文献
32.
Ali Nemati Hayati Mohammad Mehdi Ahmadi Soheil Mohammadi 《Transport in Porous Media》2012,93(1):13-27
Analytical solution of shock wave propagation in pure gas in a shock tube is usually addressed in gas dynamics. However, such
a solution for granular media is complex due to the inclusion of parameters relating to particles configuration within the
medium, which affect the balance equations. In this article, an analytical solution for isothermal shock wave propagation
in an isotropic homogenous rigid granular material is presented, and a closed-form solution is obtained for the case of weak
shock waves. Fluid mass and momentum equations are first written in wave and (mathematical) non-conservation forms. Afterwards
by redefining the sound speed of the gas flowing inside the pores, an analytical solution is obtained using the classical
method of characteristics, followed by Taylor’s series expansion based on the assumption of weak flow which finally led to
explicit functions for velocity, density and pressure. The solution enables plotting gas velocity, density and pressure variations
in the porous medium, which is of high interest in the design of granular shock isolators. 相似文献
33.
Uttiya?SenguptaEmail author Hassan?Nemati Bendiks?J.?Boersma Rene?PecnikEmail author 《Flow, Turbulence and Combustion》2017,99(3-4):909-931
This work investigates fully developed turbulent flows of carbon-dioxide close to its vapour-liquid critical point in a channel with a hot and a cold wall. Two direct numerical simulations are performed at low Mach numbers, with the trans-critical transition near the channel centre and the cold wall, respectively. An additional simulation with constant transport properties is used to selectively investigate the effect of the non-linear equation of state on turbulence. Compared to the case where the pseudo-critical transition occurs in the channel center, the case with the pseudo-critical transition close to the cold wall reveals that compressibility effects can exist in the near-wall region even at low Mach numbers. An analysis of the velocity streaks near the hot and the cold walls also indicates a greater degree of streak coherence near the cold wall. A comparison between the constant and variable viscosity cases at the same Reynolds number, Mach number and having the same isothermal wall boundary conditions reveals that variable viscosity increases turbulence near the cold wall and also causes higher velocity gradients near the hot wall. We also show that the extended van Driest transformation results in a better agreement of the velocity profile with the log-law of the wall compared to the standard van Driest transformation. The semi-locally scaled turbulent velocity fluctuations and the turbulent kinetic energy budgets on the hot and the cold sides of the channel collapse on top of each other, thereby establishing the validity of Morkovin’s hypothesis. 相似文献
34.
According to UV-visible spectroscopy, X-ray diffraction spectrometry, dynamic light scattering, Fourier transform infrared spectroscopy, electron paramagnetic resonance spectroscopy, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy, nano-sized manganese oxides are proposed as active catalysts for water oxidation in the reaction of some manganese complexes and cerium(iv) ammonium nitrate. 相似文献
35.
Ali Mohebbi Mir Ali Farajzadeh Mahboob Nemati Negin Sarhangi Mohammad Reza Afshar Mogaddam 《Biomedical chromatography : BMC》2019,33(11)
Sodium sulfate‐induced deep eutectic solvent–based solidification of floating organic droplets–dispersive liquid phase microextraction was developed prior to gas chromatography–mass spectrometry. In this method, a mixture of Na2SO4 solution (as phase separation agent and disperser) containing menthol–decanoic acid was rapidly injected into an alkaline aqueous solution containing Na2SO4. The solution was placed in an ice bath and the menthol–decanoic acid solvent was solidified on the surface of the solution. Under the optimal conditions, the enrichment factors and extraction recoveries were 122–147 and 74–89%, respectively. Finally, an aliquot of the collected organic phase was removed and mixed with acetonitrile and injected into the separation system. The limits of detection and lower limits of quantification were obtained at the ranges of 13–25 and 24–41 ng L?1, respectively. The relative standard deviations of the proposed method were ≤11% for intra‐ and inter‐day precisions at four concentrations. 相似文献
36.
Ammar R Baringer P Coppage D Davis R Haas P Kelly M Kwak N Lam H Ro S Kubota Y Nelson JK Perticone D Poling R Schrenk S Crawford G Fulton R Jensen T Johnson D Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Bortoletto D Brown DN Dominick J McIlwain RL Miller DH Modesitt M Ng CR Schaffner SF Shibata EI Shipsey IP Battle M Kroha H Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Nemati B Romero V Sun CR Wang P Zoeller MM Goldberg M Haupt T Horwitz N Jain V Kennett R Mestayer MD Moneti GC 《Physical review D: Particles and fields》1991,44(11):3383-3393
37.
Crawford G Fulton R Gan KK Jensen T Johnson DR Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Bortoletto D Brown D Dominick J McIlwain RL Miller DH Modesitt M Ng CR Schaffner SF Shibata EI Shipsey IP Battle M Kim P Kroha H Sparks K Thorndike EH Wang C Alam MS Kim IJ Nemati B Romero V Sun CR Wang P Zoeller MM Goldberg M Haupt T Horwitz N Jain V Kennett R Mestayer MD Moneti GC Rozen Y Rubin P Skwarnicki T Stone S Thusalidas M Yao W Zhu G Barnes AV Bartelt J Csorna SE Letson T Alexander J 《Physical review D: Particles and fields》1991,44(11):3394-3401
38.
Adler J Becker JJ Blaylock GT Bolton T Brown JS Bunnell KO Burnett TH Cassell RE Coffman D Cook V Coward DH Dorfan DE Dubois GP Duncan AL Eigen G Einsweiler KF Eisenstein BI Freese T Gladding G Grab C Grancagnolo F Hamilton RP Hauser J Heusch CA Hitlin DG Izen JM Köpke L Li A Lockman WS Mallik U Matthews CG Mir R Mockett PM Mozley RF Nemati B Odian A Parrish L Partridge R Perrier J Pitman D Plaetzer SA Richman JD Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Simopoulos C 《Physical review letters》1988,60(2):89-92
39.
Avery P Freyberger A Rodriguez J Yelton J Henderson S Kinoshita K Pipkin F Saulnier M Wilson R Wolinski J Xiao D Yamamoto H Sadoff AJ Ammar R Baringer P Coppage D Davis R Kelly M Kwak N Lam H Ro S Kubota Y Nelson JK Perticone D Poling R Schrenk S Alam MS Kim IJ Nemati B Romero V Sun CR Wang P Zoeller MM Crawford G Fulton R Gan KK Jensen T Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Skubic P Snow J Bortoletto D Brown DN Dominick J McIlwain RL 《Physical review letters》1992,68(9):1279-1282
40.
Coffman D DeJongh F Dubois GP Eigen G Hitlin DG Matthews CG Richman J Weinstein AJ Wisniewski WJ Zhu Y Bolton T Bunnell KO Cassell RE Coward DH Kim PC Labs J Odian A Pitman D Schindler RH Toki W Wasserbaech S Drinkard JJ Gatto C Heusch CA Lockman WS Sadrozinski HF Scarlatella M Schalk TL Seiden A Xu R Eisenstein BI Freese T Gladding G Izen JM Stockdale IE Tripsas B Mallik U Wang MZ Brown JS Burnett TH Li AD Mir R Mockett PM Nemati B Parrish L Willutzki H 《Physical review letters》1992,68(3):282-285