A numerical study of pressure fluctuations in three‐dimensional, incompressible, homogeneous, isotropic turbulence

1994 ◽  
Vol 6 (6) ◽  
pp. 2071-2083 ◽  
Author(s):  
Alain Pumir
Keyword(s):  
Isotropic Turbulence ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Homogeneous Isotropic Turbulence

scholarly journals Numerical study of pressure and velocity fluctuations in nearly isotropic turbulence

1978 ◽  
Vol 88 (4) ◽  
pp. 685-709 ◽  
Author(s):  
U. Schumann ◽  
G. S. Patterson
Keyword(s):  
Isotropic Turbulence ◽  
Initial Conditions ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Reynolds Numbers ◽  
Companion Paper ◽  
Real Space ◽  
Pressure Gradients ◽  
Velocity Statistics ◽  
Decaying Turbulence

The spectral method of Orszag & Patterson has been extended to calculate the static pressure fluctuations in incompressible homogeneous decaying turbulence at Reynolds numbers Reλ [lsim ] 35. In real space 323 points are treated. Several cases starting from different isotropic initial conditions have been studied. Some departure from isotropy exists owing to the small number of modes at small wavenumbers. Root-mean-square pressure fluctuations, pressure gradients and integral length scales have been evaluated. The results agree rather well with predictions based on velocity statistics and on the assumption of normality. The normality assumption has been tested extensively for the simulated fields and found to be approximately valid as far as fourth-order velocity correlations are concerned. In addition, a model for the dissipation tensor has been proposed. The application of the present method to the study of the return of axisymmetric turbulence to isotropy is described in the companion paper.

Three-Dimensional Computations of Turbulent Flow in a Turbine-Rotor Passage

1997 ◽  
Author(s):  
B. Song ◽  
R. S. Amano ◽  
S. Sitarama ◽  
B. Lin
Keyword(s):  
Kinetic Energy ◽  
Turbulent Flow ◽  
Isotropic Turbulence ◽  
Numerical Study ◽  
Interpolation Method ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Turbulence Kinetic Energy ◽  
Wall Region ◽  
Staggered Grids

Numerical study on a three-dimensional turbulent flow in a turbine-rotor passage is presented in this paper. The standard k-ε model was used for the first phase of the turbulence computations. The computations were further extended by employing the full Reynolds-stress closure model (RSM). The computational results obtained using these models were compared in order to investigate the turbulence effect in the near-wall region. The governing equations in a generalized curvilinear coordinate system are discretized by using the SIMPLEC method with non-staggered grids. The oscillations in pressure and velocity due to non-staggered grids are eliminated by using a special interpolation method. The predicted midspan pressure coefficients using the k-ε model and the RSM are compared with the experimental data. It was shown that the present results obtained by using either model are fairly reasonable. Computations were then extended to cover the entire blade-to-blade flow passage, and the three-dimensional effects on pressure and turbulence kinetic energy were evaluated. It was observed that the two turbulence models predict different results for the turbulence kinetic energy. This variation was identified as being related to some non-isotropic turbulence occurring near the blade surface due to the severe acceleration of the flow. It was thus proven that the models based on the RSM give more realistic predictions for highly turbulent cascade flow computations than a Boussinesq viscosity model.

One-particle two-time diffusion in three-dimensional homogeneous isotropic turbulence

2005 ◽  
Vol 17 (3) ◽  
pp. 035104 ◽  
Author(s):  
D. R. Osborne ◽  
J. C. Vassilicos ◽  
J. D. Haigh
Keyword(s):  
Isotropic Turbulence ◽  
Three Dimensional ◽  
Homogeneous Isotropic Turbulence

scholarly journals Numerical Study on the Characteristics of Pressure Fluctuations in an Axial-Flow Water Pump

2014 ◽  
Vol 6 ◽  
pp. 565061 ◽  
Author(s):  
Zhi-Jun Shuai ◽  
Wan-You Li ◽  
Xiang-Yuan Zhang ◽  
Chen-Xing Jiang ◽  
Feng-Chen Li
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Axial Flow ◽  
Rotation Frequency ◽  
Dominant Frequency ◽  
Water Pump ◽  
Flow Induced Vibration ◽  
Impeller Blade

Flow induced vibration due to the dynamics of rotor-stator interaction in an axial-flow pump is one of the most damaging vibration sources to the pump components, attached pipelines, and equipment. Three-dimensional unsteady numerical simulations were conducted on the complex turbulent flow field in an axial-flow water pump, in order to investigate the flow induced vibration problem. The shear stress transport (SST) k-ω model was employed in the numerical simulations. The fast Fourier transform technique was adopted to process the obtained fluctuating pressure signals. The characteristics of pressure fluctuations acting on the impeller were then investigated. The spectra of pressure fluctuations were predicted. The dominant frequencies at the locations of impeller inlet, impeller outlet, and impeller blade surface are all 198 Hz (4 times of the rotation frequency 49.5 Hz), which indicates that the dominant frequency is in good agreement with the blade passing frequency (BPF). The first BPF dominates the frequency spectrum for all monitoring locations inside the pump.

Effect of Struts Downstream of Low Pressure Turbine on Tone Noise Generation

2020 ◽  
Author(s):  
Ravil Nigmatullin ◽  
Larisa Terenteva
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Maximum Amplitude ◽  
Low Pressure ◽  
Mode Analysis ◽  
Low Pressure Turbine ◽  
Noise Characteristics ◽  
The Impact

Abstract In the present work a numerical study of tone noise generated by the last stage of the Low Pressure Turbine (LPT) of an aircraft engine designed for a medium-haul civilian aircraft has been conducted. The impact of struts on the tone noise characteristics is estimated. The method for turbine noise calculation is based on numerical integration of the three-dimensional unsteady Reynolds averaged Navier-Stokes equations using an in-house code for multi-stage simulations. To obtain the tonal characteristics of the generated noise, the pressure pulsation field is processed using the methods of radial mode analysis. The calculated pressure fluctuations contain all possible components of the frequency-modal spectrum, which allows us to determine profile of the generated tone noise and find propagating modes with maximum amplitude. The calculations showed that the presence of struts leads to a scattering effect, which manifests as an increase in the number of generated circumferential modes. These circumferential modes propagate both downstream and upstream and increase the total level of tone noise. The amplitudes of circumferential modes related to two different types of the interaction, rotor-stator and rotor-struts, are compared.

Numerical study on three-dimensional CJ detonation waves interacting with isotropic turbulence

2016 ◽  
Vol 61 (22) ◽  
pp. 1756-1765 ◽  
Author(s):  
Tai Jin ◽  
Kun Luo ◽  
Qi Dai ◽  
Jianren Fan
Keyword(s):  
Isotropic Turbulence ◽  
Numerical Study ◽  
Three Dimensional ◽  
Detonation Waves

Numerical Study of Pressure Fluctuations Caused by Impeller-Diffuser Interaction in a Diffuser Pump Stage

2001 ◽  
Vol 123 (3) ◽  
pp. 466-474 ◽  
Author(s):  
F. Shi ◽  
H. Tsukamoto
Keyword(s):  
Numerical Study ◽  
Complete Solution ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Sliding Mesh ◽  
Transient Flows ◽  
Singularity Method ◽  
Pump Stage

Two-dimensional and three-dimensional, unsteady state Reynolds-averaged Navier-Stokes (RANS) equations with standard k-ε turbulence models were solved within an entire stage of a diffuser pump to investigate pressure fluctuations due to the interaction between impeller and diffuser vanes. A complete solution of transient flows due to the interaction between components in the whole pump without approximating the blade count ratio of impeller to diffuser was obtained by employing an Arbitrary Sliding Mesh. The unsteady numerical results were compared with experimental data and values calculated by the singularity method. As a result of the present study, the Navier-Stokes code with the k-ε model is found to be capable of predicting pressure fluctuations in the diffuser. Furthermore, extensive numerical studies identified sources contributing to the pressure fluctuations in the diffuser, and helped to understand the mechanism of impeller-diffuser interactions in the diffuser pump.

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