Flow in a 3D diffuser

Statistical data

In this section the relevant statistical data for the diffuser computed with Alya is given. The reported data is the one mentioned in Table 2 of the list of desirable quantities (PDF) and also specified here.

The data is available as:

In CSV (text) format as profiles along characteristic lines of the diffuser
In CSV (text) format as contours along characteristic planes of the diffuser.
In HDF5 (binary) format as volumetric data.

Other turbulent statistics

Other relevant statistics from the database are presented in this section. In particular, the turbulent kinetic energy (TKE) and the characteristic length scales (i.e., the Taylor micro-scale ${\eta _{T}}$ and the Kolmogorov length-scale ${\eta _{K}}$ ) are presented in Fig. 18 along some characteristic contours of the diffuser.

Profile data

The profile data is thought to match that of the UFR_4-16_Test_Case and the experimental data. Text files (in CSV format) are provided at the streamwise locations x/h=-2, 0, 2, 4, 6, 8, 10, 12, 14, 15.5, 17, 18, 20 and 22 at the following spanwise locations z/B=0.25, 0.5, 0.75 and 0.875. Some of these profiles are also plotted below.

diffuser01_z0250_x-2_Alya_DNS	diffuser01_z0500_x-2_Alya_DNS	diffuser01_z0750_x-2_Alya_DNS	diffuser01_z0875_x-2_Alya_DNS
diffuser01_z0250_x0_Alya_DNS	diffuser01_z0500_x0_Alya_DNS	diffuser01_z0750_x0_Alya_DNS	diffuser01_z0875_x0_Alya_DNS
diffuser01_z0250_x2_Alya_DNS	diffuser01_z0500_x2_Alya_DNS	diffuser01_z0750_x2_Alya_DNS	diffuser01_z0875_x2_Alya_DNS
diffuser01_z0250_x4_Alya_DNS	diffuser01_z0500_x4_Alya_DNS	diffuser01_z0750_x4_Alya_DNS	diffuser01_z0875_x4_Alya_DNS
diffuser01_z0250_x6_Alya_DNS	diffuser01_z0500_x6_Alya_DNS	diffuser01_z0750_x6_Alya_DNS	diffuser01_z0875_x6_Alya_DNS
diffuser01_z0250_x8_Alya_DNS	diffuser01_z0500_x8_Alya_DNS	diffuser01_z0750_x8_Alya_DNS	diffuser01_z0875_x8_Alya_DNS
diffuser01_z0250_x10_Alya_DNS	diffuser01_z0500_x10_Alya_DNS	diffuser01_z0750_x10_Alya_DNS	diffuser01_z0875_x10_Alya_DNS
diffuser01_z0250_x12_Alya_DNS	diffuser01_z0500_x12_Alya_DNS	diffuser01_z0750_x12_Alya_DNS	diffuser01_z0875_x12_Alya_DNS
diffuser01_z0250_x14_Alya_DNS	diffuser01_z0500_x14_Alya_DNS	diffuser01_z0750_x14_Alya_DNS	diffuser01_z0875_x14_Alya_DNS
diffuser01_z0250_x16_Alya_DNS	diffuser01_z0500_x16_Alya_DNS	diffuser01_z0750_x16_Alya_DNS	diffuser01_z0875_x16_Alya_DNS
diffuser01_z0250_x18_Alya_DNS	diffuser01_z0500_x18_Alya_DNS	diffuser01_z0750_x18_Alya_DNS	diffuser01_z0875_x18_Alya_DNS
diffuser01_z0250_x20_Alya_DNS	diffuser01_z0500_x20_Alya_DNS	diffuser01_z0750_x20_Alya_DNS	diffuser01_z0875_x20_Alya_DNS
diffuser01_z0250_x22_Alya_DNS	diffuser01_z0500_x22_Alya_DNS	diffuser01_z0750_x22_Alya_DNS	diffuser01_z0875_x22_Alya_DNS

Characteristic Plots of these profiles are:

Figure 16: Stanford double diffuser, Re=10000, validation. Average velocities at various x/h in the vertical center plane z/B=0.5, Cherry et al. (2008) and Ohlsson et al. (2010) vs data obtained with Alya.

Figure 17: Stanford double diffuser, Re=10000, validation. Average streamwise velocity fluctuations at various x/h in the vertical center plane z/B=0.5, Cherry et al. (2008) and Ohlsson et al. (2010) vs data obtained with Alya.

Moreover, budget profiles are provided for the inlet duct area in CSV format for characteristic lines along the y and z directions. These profiles are also plotted below.

diffuser01_budgets_inletduct_y_Alya_DNS

diffuser01_budgets_inletduct_z_Alya_DNS

Figure 18: Stanford double diffuser, Re=10000. Turbulent kinetic energy budget terms in the inlet duct along the mid-channel lines. The black dashed line is the residual.

Figure 19: Stanford double diffuser, Re=10000. Streamwise Reynolds-stress budget terms in the inlet duct along the mid-channel lines. The black dashed line is the residual.

Contour data

Contour data is also provided to match that of the UFR_4-16_Test_Case and the experimental data. Text files (in CSV format) are provided at the streamwise locations x/h=2, 5, 8 and 15. These contours are also plotted below.

diffuser01_contour_x2_Alya_DNS

diffuser01_contour_x5_Alya_DNS

diffuser01_contour_x8_Alya_DNS

diffuser01_contour_x12_Alya_DNS

diffuser01_contour_x15_Alya_DNS

Characteristic plots of these contours are, on positions x/h=2, 5, 8 and 15:

Figure 20: Stanford double diffuser, Re=10000, validation. Average streamwise velocity contours, Cherry et al. (2008) and Ohlsson et al. (2010) vs data obtained with Alya. The positions of the contour planes are, from top to bottom, x/h=2, 5, 8 and 15.

Figure 21: Stanford double diffuser, Re=10000, validation. Average streamwise velocity fluctuation contours, Cherry et al. (2008) and Ohlsson et al. (2010) vs data obtained with Alya (smoothed). The positions of the contour planes are, from top to bottom, x/h=2, 5, 8 and 15.

Figure 22: Stanford double diffuser, Re=10000. Contours of turbulent kinetic energy (TKE), Taylor microscale and Kolmogorov lengthscale obtained with Alya (smoothed) in planes located, from top to bottom, at x/h=2, 5, 8 and 15.

Figure 23: Stanford double diffuser, Re=10000. Contours of Reynolds normal stresses (from left to right 11, 22, 33) obtained with Alya (smoothed) in planes located, from top to bottom, at x/h=2, 5, 8 and 15.

Figure 24: Stanford double diffuser, Re=10000. Contours of Reynolds shear stresses (from left to right 12, 13, 23) obtained with Alya (smoothed) in planes located, from top to bottom, at x/h=2, 5, 8 and 15.

Volume data

Volumetric data on the statistics computed for the whole computational domain are provided here. For more information regarding the storage format, please refer to the storage format guidelines.

The available files are, for the duct area:

Statistics (16.8 kB) Is the HDF5 master file. This is used in conjunction with the other HDF5 files to open and manage the dataset. Please refer to storage format guidelines for more information on this.
Nodes (853.5 MB) Contains the xyz positions where data is stored.
Inputs (7.8 GB) Contains the averaged pressure and velocity along with their gradients, the viscous shear stress and the Reynolds stress tensor.
Additional Quantities (1.1 GB) Contains additional quantities such as the Taylor and Kolmogorov scales and the pressure autocorrelation.
Triple Correlation (2.8 GB) Contains the components of the velocity triple correlation.
Pressure Velocity (853.5 MB) Contains the pressure velocity correlation.
Convection (1.7 GB) Contains the convection terms in the budget equations for the Reynolds stresses.
Production (1.7 GB) Contains the production terms in the budget equations for the Reynolds stresses.
Dissipation (1.7 GB) Contains the dissipation terms in the budget equations for the Reynolds stresses.
Molecular Diffusion (1.7 GB) Contains the molecular diffusion terms in the budget equations for the Reynolds stresses.
Pressure Strain (1.7 GB) Contains the pressure strain terms in the budget equations for the Reynolds stresses.
Turbulent Diffusion (1.7 GB) Contains the turbulent diffusion terms in the budget equations for the Reynolds stresses.
Pressure Diffusion (1.7 GB) Contains the pressure diffusion terms in the budget equations for the Reynolds stresses.
Residuals (1.7 GB) Contains the residual terms in the budget equations for the Reynolds stresses.
TKE budget terms (2.2 GB) Contains the terms in the budget equations for the turbulent kinetic energy (convection, production, dissipation, molecular diffusion, pressure strain, turbulent diffusion and residuals).

And, for the diffuser region:

Statistics (16.8 kB) Is the HDF5 master file. This is used in conjunction with the other HDF5 files to open and manage the dataset. Please refer to storage format guidelines for more information on this.
Nodes (1.2 GB) Contains the xyz positions where data is stored.
Inputs (10.8 GB) Contains the averaged pressure and velocity along with their gradients, the viscous shear stress and the Reynolds stress tensor.
Additional Quantities (1.5 GB) Contains additional quantities such as the Taylor and Kolmogorov scales and the pressure autocorrelation.
Pressure Velocity (1.2 GB) Contains the pressure velocity correlation.

Additional data

The following quantities are provided on all four walls as described in this document (PDF):

Pressure average ${\overline {P}}$
Pressure autocorrelation ${\overline {pp}}$
Shear stress average ${\overline {\tau _{ni}}}$
Shear stress autocorrelation ${\overline {\tau _{ni}'\tau _{nj}'}}$

This data is provided in all 4 wall planes of the computational domain

Statistics (11.9 kB) Is the HDF5 master file. This is used in conjunction with the other HDF5 files to open and manage the dataset. Please refer to storage format guidelines for more information on this.
Nodes (23.3 MB) Contains the xyz positions where data is stored.
Inputs (85.5 MB) Contains the averaged pressure and shear stress along with their autocorrelations.
Additional Quantities (116.6 MB) Contains additional quantities such as the wall normals or the gradient of pressure at the wall.

Additionally, the pressure coefficient defined as ${C_{P}=(P-P_{ref})/(0.5\rho U_{bulk})}$ , where ${P_{ref}}$ is the pressure at ${x/L=0.05}$ , is provided along the bottom wall ( ${y/h=0.0}$ ) of the diffuser, at ${z/B=0.5}$ .

diffuser01_cp_Alya_DNS

This data has been plotted together with the reference data from Cherry et al. (2008) and Ohlsson et al. (2010). As can be seen, a good agreement is reached with the existing datasets.

Figure 25: Stanford double diffuser, Re=10000, validation. Pressure coefficient along the bottom wall y/h=0 at z/B=0.5, Cherry et al. (2008) and Ohlsson et al. (2010) vs data obtained with Alya.

Contributed by: Oriol Lehmkuhl, Arnau Miro — Barcelona Supercomputing Center (BSC)

Front Page

Description

Computational Details

Quantification of Resolution

Statistical Data

Instantaneous Data

Storage Format