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douglasfowler
Posts: 2
Registered: ‎11-30-2011

How to determine water turbulence quality/Reynolds number from results?

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11-30-2011 09:21 AM

How best to determine water turbulence quality as I don't see a straightforward means of extracting Reynolds number from the results options?

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marco.mueller
Posts: 35
Registered: ‎08-30-2011

Re: How to determine water turbulence quality/Reynolds number from results?

12-01-2011 12:39 AM in reply to: douglasfowler

Hello,

 

to specify the Reynolds number you have to chose a characteristic length and velocity scale for your application which cannot be determined for most of the normal/complex applications. It is possible for simple applications like flow over a plate or inside a tube. There is an additional result quantity ("turbulence intensity") that may be helpful.

 

Usually the Reynolds number is automatically for certain areas of a simulation calculated, like an inlet face (same for Simulation CFD; see the summary file). However this does not necessarily represent the whole flow.

 

Can you provide more information about the application?



Marco Müller
Product Support Specialist
Digital Simulation
Autodesk, Inc.
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New Member
douglasfowler
Posts: 2
Registered: ‎11-30-2011

Re: How to determine water turbulence quality/Reynolds number from results?

12-02-2011 09:41 AM in reply to: marco.mueller

I am evaluating cross flow cold plate designs with the objective of maintaining laminar flow throughout all flow paths in order to minimize flow turbulence induced vibration/jitter. I calculated the inlet fow and resulting cross flow velocities that would provide Reynolds numbers less than 2000. How do I extract from a CFDesign analysis data that best correlates with localized Reynolds numbers or otherwise can be used to determine where flow is turbulent vs laminar?

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marco.mueller
Posts: 35
Registered: ‎08-30-2011

Re: How to determine water turbulence quality/Reynolds number from results?

12-05-2011 12:00 AM in reply to: douglasfowler

Please try to use the Low Re k-epsilon model, which seems to be the best fit based on your description, a good mesh resolution should be provided. Also use the additional result quantities Turbulence Intensity or Eddy Viscosity to identify possibly turbulent regions. My personal guess is that you cannot extract Reynolds numbers for this specific type of flow that will give you the information whether the flow is turbulent or not like for a simple tube flow.



Marco Müller
Product Support Specialist
Digital Simulation
Autodesk, Inc.
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