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Old   May 14, 2010, 02:17
Default Domain for external flow
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I wish to raise some discussion points here on determining the best suitable type of domain shape for external flow. As we know, always there will be questions on "how large" or what should be the extend of domain size for external flow.

Typically there are a few approaches available:

1. to use a rectangular box with the size extended 5 to 10 times the characteristic length of the geometry/ object under simulation.
2. to use a sphere enveloping the object under simulation
3. to use a semi sphere

The later two (2. and 3.) are said good to eliminate some edge effect at the corners of the domain which happens in 1.

Does anyone has any experience with this method of modeling? Appreciate to receive some comments/ opinions/ advice from the fellow experts in CFDOnline.

Thx & Cheers
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Old   May 14, 2010, 11:37
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Quote:
Originally Posted by chinc View Post
I wish to raise some discussion points here on determining the best suitable type of domain shape for external flow. As we know, always there will be questions on "how large" or what should be the extend of domain size for external flow.

Typically there are a few approaches available:

1. to use a rectangular box with the size extended 5 to 10 times the characteristic length of the geometry/ object under simulation.
2. to use a sphere enveloping the object under simulation
3. to use a semi sphere

The later two (2. and 3.) are said good to eliminate some edge effect at the corners of the domain which happens in 1.

Does anyone has any experience with this method of modeling? Appreciate to receive some comments/ opinions/ advice from the fellow experts in CFDOnline.

Thx & Cheers
I'm definitely not an expert, but this is what I usually do:

external-topology.jpg

I think blocking this way allows more control over the grid density. (I color-coded the edges to show what I mean. The edges with the same color would have the same grid density.) Also, it keeps the boundary layer grid from extending into the far field, reducing the total number of gridpoints.
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Old   August 8, 2010, 01:23
Question Domain for external flow
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Ramakrishnan Ramaswamy
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Hi friends, can anyone help me how to fix a domain for external flow. I am analysing flow over a swept wing. Can i choose a circular domain or rectangular one or oval shape, What is the significance one over the other?
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