Relevant bibliographies by topics / Root-mean-square fluctuation

Academic literature on the topic 'Root-mean-square fluctuation'

Author: Grafiati
Published: 6 September 2023

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Journal articles on the topic "Root-mean-square fluctuation"

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Cai, Jian-Cheng, Hao-Jie Chen, Volodymyr Brazhenko, and Yi-Hong Gu. "Study of the Hydrodynamic Unsteady Flow Inside a Centrifugal Fan and Its Downstream Pipe Using Detached Eddy Simulation." Sustainability 13, no. 9 (May 2, 2021): 5113. http://dx.doi.org/10.3390/su13095113.

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The detailed unsteady turbulent flow inside a centrifugal fan and its downstream pipe was studied using detached eddy simulation (DES) at three flowrates, namely, the best efficiency point (BEP), 0.75BEP, and 1.49BEP. Both the mean and fluctuating flow fields were analyzed on the basis of the root-mean-square value as the indication of fluctuating intensity. Results showed that the pressure fluctuation had the minimum value at BEP, but the velocity fluctuation increased with the flowrate. Most regions inside the centrifugal fan underwent large pressure fluctuation with the magnitude of about 10~20% of pref = 0.5 ρu22, where u2 is the blade velocity at the impeller outlet. The pressure fluctuation had a maximum value at the impeller side of the tongue tip rather than the stagnation point, and it decreased rapidly along the outlet pipe with magnitude about 1% of pref after distance of five pipe diameters. The spectra of hydrodynamic pressure showed conspicuous spikes at the blade passing frequency (BPF) in the volute but not in the downstream pipe. At the downstream pipe entrance, pressure fluctuation spectra agreed with experimental results, showing that hydrodynamic pressure fluctuations were dominant; however, the experimental data showed a much slower decreasing rate due to the acoustic fluctuations.
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Lu, Tao, Su Mei Liu, Ping Wang, and Wei Yyu Zhu. "Larger-Eddy Simulation of Velocity Fluctuation in a Mixing T-Junction." Applied Mechanics and Materials 152-154 (January 2012): 1313–18. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.1313.

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Velocity fluctuations in a mixing T-junction were simulated in FLUENT using large-eddy simulation (LES) turbulent flow model with sub-grid scale (SGS) Smagorinsky–Lilly (SL) model. The normalized mean and root mean square velocities are used to describe the time-averaged velocities and the velocities fluctuation intensities. Comparison of the numerical results with experimental data shows that the LES model is valid for predicting the flow of mixing in a T-junction junction. The numerical results reveal the velocity distributions and fluctuations are basically symmetrical and the fluctuation at the upstream of the downstream of the main duct is stronger than that at the downstream of the downstream of the main duct.
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Suzuki, Y., M. Kiya, T. Sampo, and Y. Naka. "Pressure Fluctuations on the Surface of a Hemisphere Immersed in a Thick Turbulent Boundary Layer." Journal of Fluids Engineering 109, no. 2 (June 1, 1987): 130–35. http://dx.doi.org/10.1115/1.3242632.

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Statistical properties of pressure fluctuations on the surface of a hemisphere immersed in a thick turbulent boundary layer are described. The height of the hemisphere tested was 0.275 thicknesses of the boundary layer. Reynolds number based on the model diameter D and the time-mean approaching flow velocity at the level of the top Ur was 3.0 × 105. Time-mean and root-mean-square (rms) values, probability density and power spectra of the pressure fluctuations are presented and discussed. The pressure fluctuations are related to the fluctuating approaching-flow velocity in terms of the pressure-velocity admittance and the cross correlation. Main results are that the time-mean and rms pressures attained a primary maximum at the front stagnation point; that the pressure-velocity admittance near the front stagnation point was approximately unity at frequencies less than about 0.4 Ur/D; that the pressure fluctuation in front of the hemisphere is positively correlated with that in the rear side and negatively correlated with that in the middle.
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Tsekov, Roumen. "Brownian Emitters." Fluctuation and Noise Letters 15, no. 04 (September 29, 2016): 1650022. http://dx.doi.org/10.1142/s021947751650022x.

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A Brownian harmonic oscillator, which dissipates energy either by friction or via emission of electromagnetic radiation, is considered. This Brownian emitter is driven by the surrounding thermo-quantum fluctuations, which are theoretically described by the fluctuation–dissipation theorem. It is shown how the Abraham–Lorentz force leads to dependence of the half-width on the peak frequency of the oscillator amplitude spectral density. It is found that for the case of a charged particle moving in vacuum at zero temperature, its root-mean-square velocity fluctuation is a universal constant, equal to roughly 1/18 of the speed of light. The relevant Fokker–Planck and Smoluchowski equations are also derived.
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Li, Yuepeng, Liuyue Wang, Xun Zou, Jihong Qu, and Gang Bai. "Experimental and Simulation Research on the Process of Nitrogen Migration and Transformation in the Fluctuation Zone of Groundwater Level." Applied Sciences 12, no. 8 (April 8, 2022): 3742. http://dx.doi.org/10.3390/app12083742.

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The fluctuation of groundwater causes a change in the groundwater environment and then affects the migration and transformation of pollutants. To study the influence of water level fluctuations on nitrogen migration and transformation, physical experiments on the nitrogen migration and transformation process in the groundwater level fluctuation zone were carried out. A numerical model of nitrogen migration in the Vadose zone and the saturated zone was constructed by using the software HydrUS-1D. The correlation coefficient and the root mean square error of the model show that the model fits well. The numerical model is used to predict nitrogen migration and transformation in different water level fluctuation scenarios. The results show that, compared with the fluctuating physical experiment scenario, when the fluctuation range of the water level increases by 5 cm, the fluctuation range of the nitrogen concentration in the coarse sand, medium sand and fine sand media increases by 37.52%, 31.40% and 21.14%, respectively. Additionally, when the fluctuation range of the water level decreases by 5 cm, the fluctuation range of the nitrogen concentration in the coarse sand, medium sand and fine sand media decreases by 36.74%, 14.70% and 9.39%, respectively. The fluctuation of nitrogen concentration varies most significantly with the amplitude of water level fluctuations in coarse sand; the change in water level has the most significant impact on the flux of nitrate nitrogen and has little effect on the change in nitrite nitrogen and ammonium nitrogen, and the difference in fine sand is the most obvious, followed by medium sand, and the difference in coarse sand is not great.
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Saavedra, L. G. P. "Geometric Factors in Electromagnetic Field Commutators and the Quantum Information Control of Vacuum Fluctuations." Open Systems & Information Dynamics 14, no. 03 (September 2007): 319–32. http://dx.doi.org/10.1007/s11080-007-9055-1.

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The electromagnetic field commutation relations are defined in terms of geometric factors that are double averages over two finite four-dimensional space-time regions. The square root of any of the uncertainty relations derived from the aforementioned commutators is taken as a critical field, in the sense that any electromagnetic field much larger than it can be treated as classical. Another critical electromagnetic field associated with the quantum information control of vacuum fluctuations can be chosen as the square root of the mean quadratic fluctuation of each quantity of electromagnetic field, when the number of photons is defined and is equal to zero. Any electromagnetic field expectation value could be measured if it is much greater than the last critical field. This article covers a magnitude order comparison between the critical fields and its consequences for measuring the electromagnetic field information.
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Cho, Soo-Hwan, and Sang-Gyun Kang. "Application of the Combined Kalman Filter and Root-Mean-Square Method to Detection of Voltage Fluctuation." Advanced Science Letters 8, no. 1 (April 15, 2012): 649–53. http://dx.doi.org/10.1166/asl.2012.2457.

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Kysela, Bohuš, Jiří Konfršt, Ivan Fořt, Michal Kotek, and Zdeněk Chára. "Study of the Turbulent Flow Structure around a Standard Rushton Impeller." Chemical and Process Engineering 35, no. 1 (March 1, 2014): 137–47. http://dx.doi.org/10.2478/cpe-2014-0010.

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Abstract The velocity field around the standard Rushton turbine was investigated by the Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV) measurements. The mean ensembleaveraged velocity profiles and root mean square values of fluctuations were evaluated at two different regions. The first one was in the discharge stream in the radial direction from the impeller where the radial flow is dominant and it is commonly modelled as a swirling turbulent jet. The validity range of the turbulent jet model was studied. The second evaluated region is under the impeller where flow seems to be at first sight rather rigorous but obtained results show nonnegligible values of fluctuation velocity.
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Spangler, S. R. "The small amplitude of density turbulence in the inner solar wind." Nonlinear Processes in Geophysics 10, no. 1/2 (April 30, 2003): 113–20. http://dx.doi.org/10.5194/npg-10-113-2003.

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Abstract. Very Long Baseline Interferometer (VLBI) observations were made of radio sources close to the Sun, whose lines of sight pass through the inner solar wind (impact parameters 16-26 RE). Power spectra were analyzed of the interferometer phase fluctuations due to the solar wind plasma. These power spectra provide information on the level of plasma density fluctuations on spatial scales of roughly one hundred to several thousand kilometers. By specifying an outer scale to the turbulence spectrum, we can estimate the root-mean-square (rms) amplitude of the density fluctuations. The data indicate that the rms fluctuation in density is only about 10% of the mean density. This value is low, and consistent with extrapolated estimates from more distant parts of the solar wind. Physical speculations based on this result are presented.
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Lu, Tao, Yong Wei Wang, and Ping Wang. "Large Eddy Simulation with Three Kinds of Sub-Grid Scale Model on Temperature Fluctuation of Hot and Cold Fluids Mixing in a Tee." Applied Mechanics and Materials 152-154 (January 2012): 1307–12. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.1307.

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In the present work the temperature fluctuations in a mixing tee were simulated on FLUENT platform using the large-eddy simulation (LES) turbulent flow model with three kinds of sub-grid scale (SGS) models such as Smagorinsky-Lilly (SL) model, Wall-adapted Local Eddy-viscosity (WALE) model, and Kinetic-energy transport (KET) model. The normalized mean and root mean square temperatures were predicted and analyzed with consideration of buoyancy. The numerical results showed that buoyancy greatly influences the mixing flow and the thermal striping phenomena were quite obvious. These three SGS models have somewhat similar accuracies for prediction of the temperature fluctuation and thermal stripping in a tee of mixing hot and cold fluids.
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Dissertations / Theses on the topic "Root-mean-square fluctuation"

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Alladin, Muttaqi Ahmad. "Assessing protein contribution to phenotypic change using short, coarse grained molecular dynamics simulations." Thesis, 2023. https://etd.iisc.ac.in/handle/2005/6073.

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Understanding the functional mapping between genotype and phenotype is an important problem that has ramifications for various diseases. Various existing computational methods can infer these disease-related functional mappings. Molecular dynamics (MD) is one such advantageous method that does not rely on prior information or learning, as they use the first principles (Newton's laws of motion) to determine protein movement. Thus, they are suited for understanding and rationally evaluating phenotype alteration with minimal bias. However, MD simulations are computationally expensive and require a lot of resources and time. Therefore, using lengthy all-atom MD simulations to reproduce microsecond to millisecond scale biological phenomena is prohibitive. A previous study assessing phenotype alteration recorded the structure's root-mean-square fluctuation (RMSF) from a coarse-grained MD simulation of 1 microsecond. Our study uses a short coarse-grained MD simulation (<10 nanoseconds) to generate the RMSF data in combination with a new scoring function for prediction. The designed scoring function captures the changes in the RMSF between the wild type and the variant, normalized for comparison. The shortened simulation time allows us to evaluate more variants in a reasonable time. We predicted phenotype change scores for 14,691 variants of Calmodulin, SUMO-conjugating enzyme UBC9 (UBE2I), Small ubiquitin-related modifier 1 (SUMO1), and Methylenetetrahydrofolate reductase (MTHFR) catalytic and regulatory domains, for which quantitative experimental data as a variant phenotype score was available. We found a high Pearson correlation coefficient when calculating the values at various minor levels of outlier exclusion. We obtained a consistently superior performance for all proteins except for the catalytic domain of MTHFR when compared against the state-of-the-art machine learning-based method Polyphen2. The performance of the catalytic domain of MTHFR was comparable to that of Polyphen2. We analyzed our results across all proteins to understand why the prediction erred on a subset of variants. We believe that the insights gained from this work will help strengthen the rational interpretation of single nucleotide polymorphism of the genome in the context of observed phenotypic change.
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Books on the topic "Root-mean-square fluctuation"

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Chen, Y. S. A root-mean-square pressure fluctuations model for internal flow applications. [Washington, DC]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.

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United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch., ed. A root-mean-square pressure fluctuations model for internal flow applications. [Washington, DC]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.

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Chen, Y. S. A root-mean-square pressure fluctuations model for internal flow applications. [Washington, DC]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.

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A root-mean-square pressure fluctuations model for internal flow applications. [Washington, DC]: National Aeronautics and Space Administration, Scientific and Technical Information Branch, 1985.

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Book chapters on the topic "Root-mean-square fluctuation"

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Schulman, L. S. "Ferromagnetism." In When Things Grow Many, 50–62. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780198861881.003.0005.

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Abstract Magnetism and order parameters are discussed in both mean field theory and exact treatments. An example of stochastic dynamics for the Ising model is given. The Curie–Weiss model is defined as a system in which mean field theory is exact. For this system (consisting of N spins) the fluctuations at the critical point are the fourth root of N, rather than the square root as is the case when the variables are independent.
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Ben Amira, Bilel, Mariem Ammar, Ahmad Kaffel, Zied Driss, and Mohamed Salah Abid. "The Effects of Curved Blade Turbine on the Hydrodynamic Structure of a Stirred Tank." In Vortex Dynamics Theories and Applications. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.92394.

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This work is aimed at studying the hydrodynamic structure in a cylindrical stirred vessel equipped with an eight-curved blade turbine. Flow fields were measured by two-dimensional particle image velocimetry (PIV) to evaluate the effect of the curved blade turbine. Velocity field, axial and radial velocity distribution, root mean square (rms) of the velocity fluctuations, vorticity, and turbulent kinetic energy were presented. Therefore, two recirculation loops were formed close to the free surface and in the bottom of the tank. Moreover, the highest value area of the vorticity is localized in the upper region of the tank which follows the same direction of the first circulation loop. The turbulent kinetic energy is maximum at the blade tip following the trailing vortices.
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Conference papers on the topic "Root-mean-square fluctuation"

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Lawson, Anthony L., and Ramkumar N. Parthasarathy. "An Analytical Study of Turbulent Dispersion of Bubbles." In ASME 2001 Engineering Technology Conference on Energy. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/etce2001-17016.

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Abstract An analysis of the dispersion of bubbles in homogenous and isotropic turbulent liquid flows was performed to study the effects of bubble and flow characteristics on their dispersion. Bubbles were assumed to be spherical and to follow the fluid motion in the mean. No mass transfer occurred between the bubble and liquid; also, there was no interaction between individual bubbles. It was found that for accurate prediction of bubble dispersion requires a simultaneous consideration of the inertia of the added mass of liquid (because the inertia of the bubble itself is small) and the bubble rise velocity. Normalized bubble diffusivity, root-mean-square fluctuating velocity, and Lagrangian integral time scale were related to two non-dimensional parameters: ratio of the added mass response time to the liquid flow integral time scale, and the ratio of the bubble rise velocity to the root-mean-square liquid velocity fluctuation. In general, the bubble Lagrangian velocity auto-correlations decreased as the rise velocity ratio increased. The dependence of the autocorrelations on the time-scale ratio was complex. A surprising result was that the bubble velocity fluctuations could exceed the liquid velocity fluctuations for certain conditions because of their low inertia.
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Bataille, Franc¸oise, and Guillaume Brillant. "Large-Eddy Simulation of a Turbulent Boundary Layer With Blowing." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45343.

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The modifications of a turbulent boundary layer induced by blowing through a porous plate are investigated using large-eddy simulation. The Reynolds number (based on the length of the plate) of the boundary layer is about 850,000. In order to simulate the fully developed turbulent boundary layer, an instationnary inflow condition is used. Influences of the fluid injection rate upon the three components of the velocity are characterized and a good agreement is obtained when comparing with previous experimental measures. Evolution of the mean and root-mean square parts of the velocity with injection rate is studied. It is observed that the maximum of the fluctuations of the longitudinal velocity slowly increases with blowing but the size of the domain where the fluctuation level is high, rapidly grows. For the vertical and transverse components, the fluctuating profiles are almost multiplied by two. Finally, blowing is shown to increase the level of the near-wall structures as well as the physical space where they develop.
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Bai, Bofeng, Tiejun Wu, Liejin Guo, and Xuejun Chen. "Pressure Drop Fluctuation and Flow Regime Identification for Air-Water Two-Phase Flow." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2059.

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Abstract The fluctuating pressure drop for air-water two-phase flow was measured in the vertical upward section of U-type tube with 0.05m I.D. The feature of the fluctuations was extracted by means of statistical and chaotic theories. The influence of liquid superficial velocity on the features was also investigated. The results showed that the mean, root mean square, fractal dimension of pressure drop fluctuations is function of flow regimes. The fractal dimension can be larger than 1.5 in annular flow with great liquid superficial velocity which is reported for the first time. Furthermore, the present paper provided a feasible solution, which the gas-liquid two-phase flow regimes can be recognized automatically and objectively on basis of the combination of the Counter Propagation Network (CPN) and the FFT coefficients of the differential pressure fluctuations. The recognition possibility is determined by the clustering results of the Kohonen layer in the CPN. With the presented test cases, the possibility can be greater than 90 percent for different liquid phase velocity.
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Choi, Seok-Ki, Ho-Yun Nam, Myung-Hwan Wi, Seong-O. Kim, Jong-Chull Jo, and Hoon-Ki Choi. "Evaluation of Turbulence Models for Thermal Striping in a Triple-Jet." In ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71512.

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A computational study for the evaluation of the current turbulence models for the prediction of a thermal striping in a triple-jet is performed. The tested turbulence models are the two-layer model, the shear stress transport model and the elliptic relaxation model. These three turbulence models are applied to the prediction of the thermal striping in a triple-jet in which detailed experimental data are available. The performances of the tested turbulence models are evaluated through comparisons with the experimental data. The predicted mean and root-mean-square values of the temperature are compared with the experimental data, and the capability of predicting the oscillatory behavior of the ensemble-averaged temperature is investigated. From these works it is shown that only the elliptic relaxation model is capable of predicting the oscillatory behavior of the ensemble-averaged temperature. It is also shown that the elliptic relaxation model predicts best the time-averaged and root-mean-square of the temperature fluctuation. However, this model predicts a slower mixing at the far downstream of the jet.
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Ikeda, Jun, Javier Sanchez Rios, Naoshi Kuratani, Kenta Ogawa, and Makoto Tsubokura. "Numerical Investigation of Fluctuating Aerodynamic Lift Acting on the Road Vehicle Which Affects Drivability." In ASME-JSME-KSME 2019 8th Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/ajkfluids2019-5253.

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Abstract In this study, unsteady flow simulations using a large-eddy simulation are conducted to analyze vehicle aerodynamics. The objective is to investigate flow structures that cause unsteady lift fluctuations potentially affecting the drivability of a vehicle. In addition, the dependence on the yaw angle of the incoming flow yaw angle is studied. The target model is a sedan-type vehicle that includes a complex underbody geometry and engine compartment. The model is based on production CAD drawings. The yaw angle of the incoming flow is set to 0°, 3°, and 5°. The simulation results are analyzed by several post-processing methods, such as root-mean-square of the transient pressure field, power spectral density of the lift force, and dynamic mode decomposition method to extract the flow features associated with the unsteady lift fluctuation. It is concluded that the aerodynamic fluctuation that may affect a vehicle’s vertical stability is concentrated on the rear tire and bumper area. In addition, when the yaw angle of the incoming flow increases, the fluctuation of the lift and the disturbance of flow structures are enhanced.
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Park, Su-Ki, and Moohwan Kim. "Turbulent Boundary Layer of Vapor Phase on a Wavy Falling-Film Condensation of Steam-Air Mixture." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0764.

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Abstract The wave structure of condensate film and the characteristics of boundary layer flow in the vapor phase were investigated experimentally for condensation of steam-air mixture on a vertical surface. The instantaneous film thickness and the fluctuating temperature in the boundary layer were measured simultaneously. Also the heat transfer coefficient across the condensate film and the diffusion layer formed by air (noncondensable gas) was obtained at various film Reynolds numbers and vapor velocities. The influence of the wavy interface on the temperature field and the heat transfer depend strongly on film Reynolds number and vapor velocity. The condensation heat transfer coefficient increases more than several tens percents with the increase of film Reynolds number depending on the vapor velocity. The fluctuating temperature correlates strongly with the waviness of condensate film corresponding to film Reynolds number. The RMS (root-mean-square) of the temperature fluctuation increases considerably due to the waviness and shows a maximum value around the crest of large amplitude waves.
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Dimić, Dušan, Dejan Milenković, Edina Avdović, Goran Kaluđerović, and Jasmina Dimitrić Marković. "MOLECULAR DOCKING AND MOLECULAR DYNAMICS STUDIES OF THE INTERACTION BETWEEN COUMARIN-NEUROTRANSMITTER DERIVATIVES AND CARBONIC ANHYDRASE IX." In 1st INTERNATIONAL Conference on Chemo and BioInformatics. Institute for Information Technologies, University of Kragujevac,, 2021. http://dx.doi.org/10.46793/iccbi21.056d.

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Novel biologically active compounds can be obtained by the structural modification of coumarins. In this contribution, five new derivatives of 4-hydroxycoumarin with tyramine, octopamine, norepinephrine, 3-methoxytyramine, and dopamine were obtained. Their structures were optimized based on the previously obtained crystal structure of the 4-hydroxycoumarin-dopamine derivative. The special emphasis was put on the effect of various substituents on the structure of obtained compounds and intramolecular interactions governing the stability. To investigate their possible antitumor activity, molecular docking and molecular dynamics simulations were performed with Carbonic anhydrase, a prognostic factor in several cancers, and compared to the native ligand, 5-acetamido-1,3,4-thiadiazole- 2-sulfonamide. The results have shown that all of the coumarin-neurotransmitter derivatives bind to the active pocket of protein with the binding energies higher than for the native ligand. The main contributions to the binding energies were discussed. The Root Mean Square Deviation (RMSD), Root Mean Square Fluctuation (RMSF), and Radius of gyration (Rg), as results of MD simulations, were used to predict the activity of compounds towards chosen protein. The highest MD binding energies were obtained for the derivatives with dopamine and 3-methoxytyramine, with the van der Waals interaction and hydrogen bonds being the most important contributors.
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Xu, Hening, Shota Ishitsuka, Masaaki Motozawa, Kaoru Iwamoto, Hirotomo Ando, Tetsuya Senda, Bo Yu, and Yasuo Kawaguchi. "Structure of Low-Speed Streaks in Drag Reducing Flow With Polymer Solution Blown From the Channel Wall." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44462.

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For the investigation of turbulent structure in drag reducing flow with polymer solution blown from the channel wall (wall blowing), instantaneous velocity field has been precisely measured in the x-z plane at different locations along the wall-normal direction via Particle Image Velocimetry (PIV). Polymer solutions with 25 ppm and 100 ppm of weight concentration were tested at a blowing ratio of 1.2×10−4 and at 20000 of Reynolds number. About 5% and 11% of drag reduction (DR) rate was obtained, respectively. As a result of this experiment, turbulent statistic data showed that the Root Mean Square (RMS) of streamwise velocity fluctuation increased and RMS of spanwise velocity fluctuation was suppressed comparing with water flow. We found that these low-speed streaks became relatively regular in the buffer layer, including an increase of both length and width, which indicated a depression of turbulence by polymer diffused in the buffer layer.
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Jia, Huixia, and Konrad Vogeler. "Effect of Clocking on the Unsteady Rotor Blade Loading in a 1.5-Stage Low-Speed Axial Compressor." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27237.

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This paper presents the effect of clocking on the unsteady loading of the rotor blades in the first stage with an inlet guide vane row (IGV) of the Dresden Low-Speed Research Compressor (LSRC). The unsteady flow field of the Dresden LSRC at 10 IGV clocking positions for the design point was investigated using a 3D time-accurate viscous solver. The time-averaged pressure distributions on the pressure side (PS) and the suction side (SS) of the rotor blades at midspan (MS) are presented for different clocking positions. The effect of the clocking on the time-averaged Root Mean Square-value (RMS) of the unsteady pressure fluctuations of the rotor blades at MS is investigated. The unsteady pressure fluctuations on the PS and the SS of the rotor blades at MS for different clocking positions are presented and discussed. The unsteady blade pressure forces on the rotor blades, which are calculated from the profile pressure distributions, are presented and analysed for different clocking positions. The maximal fluctuation amplitude of the unsteady pressure forces on the rotor blades, which fluctuate around the nearly identical mean values for different clocking positions, can be reduced about 60 percent with the IGV clocking for the design point in the investigated configuration. The effect of the clocking on the time-resolved inlet- and outlet flow fields of the rotor blades is investigated and discussed.
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Feng, Zhipeng, Liwen Deng, Xuan Huang, Pingchuan Shen, Shuai Liu, and Fengchun Cai. "Research on Characteristics of Fluid Exciting Force of Reactor Internals." In ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-62128.

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Abstract Flow-induced vibration is an important issue related to the safety and reliability of nuclear reactor, which need to be analyzed and evaluated in the design stage. In order to obtain the input loads and key parameters used in the calculation of flow-induced vibration of reactor vessel internals (RVIs) that need to satisfy the engineering requirements. The typical RVIs are selected as the research object, and the fluid exciting force characteristics are studied based on the computational fluid dynamics methods. The results show that the fluid exciting force acting on the RVIs is a wide-band stochastic process. For upper internal, the largest pressure fluctuation occurs at the guide tubes and support columns located near the outlet. Therefore, it is necessary to pay more attention to these guide tubes and support columns in response analysis. As for core barrel, the root mean square value of the pressure fluctuation changes drastically at the inlet and outlet location. For lower internal, the lower flow field of RVIs is relatively disordered, and its pressure fluctuation possesses irregular characteristics. Each component of lower internal need to be considered in analysis and evaluation.
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