Difference between revisions of "Best Practice Advice AC3-10"

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(New page: ='''Combining/dividing flow in Y junction'''= '''Application Challenge 3-10''' © copyright ERCOFTAC 2004 =='''Best Practice Advice for the AC'''== '''Key Fluid Physics...)
 
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='''Combining/dividing flow in Y junction'''=
 
='''Combining/dividing flow in Y junction'''=
  
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'''Key Fluid Physics'''
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===Key Fluid Physics===
  
 
The application challenge on which this best practice advice is based is associated with the flow of water in a Y-junction, Reference 1. The flow is characterised by the following elements:
 
The application challenge on which this best practice advice is based is associated with the flow of water in a Y-junction, Reference 1. The flow is characterised by the following elements:
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'''Application Uncertainties'''
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===Application Uncertainties===
  
 
The application uncertainties associated with the Application Challenge are as follows:
 
The application uncertainties associated with the Application Challenge are as follows:
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'''Computational Domain and Boundary Conditions'''
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===Computational Domain and Boundary Conditions===
  
 
With respect to the computational domain and boundary conditions, the following best practice advice is appropriate:
 
With respect to the computational domain and boundary conditions, the following best practice advice is appropriate:
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'''Discretisation and Grid Resolution'''
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===Discretisation and Grid Resolution===
  
 
With respect to discretisation and grid resolution, the following best practice advice is appropriate:
 
With respect to discretisation and grid resolution, the following best practice advice is appropriate:
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'''Physical Modelling'''
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===Physical Modelling===
  
 
With respect to physical modelling the following BPA is appropriate:
 
With respect to physical modelling the following BPA is appropriate:
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'''Recommendations for Future Work'''
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===Recommendations for Future Work===
  
 
The following recommendations for future work are appropriate:
 
The following recommendations for future work are appropriate:
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Site Design and Implementation: [[Atkins]] and [[UniS]]
 
Site Design and Implementation: [[Atkins]] and [[UniS]]
 
 
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{{AC|front=AC 3-10|description=Description_AC3-10|testdata=Test Data_AC3-10|cfdsimulations=CFD Simulations_AC3-10|evaluation=Evaluation_AC3-10|qualityreview=Quality Review_AC3-10|bestpractice=Best Practice Advice_AC3-10|relatedUFRs=Related UFRs_AC3-10}}

Revision as of 10:25, 19 March 2009

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Best Practice Advice

Combining/dividing flow in Y junction

Application Challenge 3-10 © copyright ERCOFTAC 2004


Best Practice Advice for the AC

Key Fluid Physics

The application challenge on which this best practice advice is based is associated with the flow of water in a Y-junction, Reference 1. The flow is characterised by the following elements:

• Steady, turbulent and incompressible flow.

• Flow separation.

• Mixing.

• A Reynolds Number between 5x105 and 1.2x106.


Application Uncertainties

The application uncertainties associated with the Application Challenge are as follows:

• Turbulence at the Y-junction inlets. It was assumed that the upstream pipework was sufficiently long for the inlet flow to the computational domain to be fully-developed.

• Use of wall functions. Flow separation can occur in the Y-junction. Within separated regions and flow recirculations the standard wall function approach is unreliable.

• Choice of turbulence model. The simple k-epsilon turbulence model performs less well than more sophisticated methods, e.g. Differential Stress.

The sensitivity of the DOAP to these application uncertainties is relatively small.


Computational Domain and Boundary Conditions

With respect to the computational domain and boundary conditions, the following best practice advice is appropriate:

• It is acceptable to model half of the Y-junction, on one side of the symmetry plane.

• Use mass-flow boundaries at the inlets and exits of the Y-junction, with fully-developed velocity profiles.

• For best accuracy, use the Differential Stress turbulence model, with standard wall functions.


Discretisation and Grid Resolution

With respect to discretisation and grid resolution, the following best practice advice is appropriate:

• Standard (hybrid) spatial discretisation schemes are adequate.

• The grid must be sufficiently fine to resolve the details of the flow. A constant near-wall cell size is recommended.


Physical Modelling

With respect to physical modelling the following BPA is appropriate:

• Assume that the flow is turbulent.

• Assume that the fluid is isothermal and incompressible.


Recommendations for Future Work

The following recommendations for future work are appropriate:

• Do further CFD calculations using finer grids.

• Perform further experiments to measure velocities and turbulence quantities within the Y-junction.


References

1. Combining/Dividing Flow in a Y-Junction

AC3-10 D30, July 2002


© copyright ERCOFTAC 2004


Contributors: Alan Stevens - Rolls-Royce Marine Power, Engineering & Technology Division

Site Design and Implementation: Atkins and UniS


Front Page

Description

Test Data

CFD Simulations

Evaluation

Best Practice Advice