Difference between revisions of "UFR 4-08 Best Practice Advice"

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The best practice advice is based on the only known and available numerical computation performed by Wang (1991).
The best practice advice is based on the only known and available numerical computation performed by Wang (1991).


''Key Physics:''
=== Key Physics ===


* turbulent flow with streamline curvature, axi-symmetric separation and flow re-attachment
* turbulent flow with streamline curvature, axi-symmetric separation and flow re-attachment


''Numerical Modelling Issues:''
=== Numerical Modelling Issues ===


* an two-dimensional axi-symmetric calculation captures the main features of the flow
* an two-dimensional axi-symmetric calculation captures the main features of the flow
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* the computational domain needs to insure a long enough inflow and outflow region
* the computational domain needs to insure a long enough inflow and outflow region


''Physical Modelling:''
=== Physical Modelling ===


* the standard k-ε turbulence model with wall functions can provide a reasonable good prediction of the turbulent kinetic energy field
* the standard k-ε turbulence model with wall functions can provide a reasonable good prediction of the turbulent kinetic energy field
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* the result for mean velocities and turbulence intensities seems to be quite sensitive to the specification of the dissipation rate at the inlet cross-section
* the result for mean velocities and turbulence intensities seems to be quite sensitive to the specification of the dissipation rate at the inlet cross-section


''Recommendation for Future Work:''
=== Recommendation for Future Work ===


* the application of a full Reynolds stress turbulence model should be able also to predict the anisotropy of the turbulence and will also allow to predict the shear stresses
* the application of a full Reynolds stress turbulence model should be able also to predict the anisotropy of the turbulence and will also allow to predict the shear stresses

Revision as of 10:16, 9 March 2009


Front Page

Description

Test Case Studies

Evaluation

Best Practice Advice

References




Orifice/deflector flow

Underlying Flow Regime 4-08               © copyright ERCOFTAC 2004


Best Practice Advice

Best Practice Advice for the UFR

The best practice advice is based on the only known and available numerical computation performed by Wang (1991).

Key Physics

  • turbulent flow with streamline curvature, axi-symmetric separation and flow re-attachment

Numerical Modelling Issues

  • an two-dimensional axi-symmetric calculation captures the main features of the flow
  • a grid with 128x28 cells with a refinement near the orifice allowed an accurate prediction of the re-attachment length
  • a second order scheme for the diffusion terms and a hybrid scheme for the convective terms is advisable
  • the computational domain needs to insure a long enough inflow and outflow region

Physical Modelling

  • the standard k-ε turbulence model with wall functions can provide a reasonable good prediction of the turbulent kinetic energy field
  • the result for mean velocities and turbulence intensities seems to be quite sensitive to the specification of the dissipation rate at the inlet cross-section

Recommendation for Future Work

  • the application of a full Reynolds stress turbulence model should be able also to predict the anisotropy of the turbulence and will also allow to predict the shear stresses

© copyright ERCOFTAC 2004



Contributors: Martin Sommerfeld - Martin-Luther-Universitat Halle-Wittenberg


Front Page

Description

Test Case Studies

Evaluation

Best Practice Advice

References