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how to know when mesh is sufficiently refined?

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Old   April 14, 2020, 11:45
Default how to know when mesh is sufficiently refined?
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Josh McCraney
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Hi FOAMers!

I'm running a simulation in interFoam, and it takes a long time to run. The simulation is simply liquid being drained from a container in zero gravity, and the tank is a little smaller than a mailbox (160 mm in length). Before running the simulation I would like to know if my mesh is sufficiently refined. How would you do this?
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Old   April 14, 2020, 17:11
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That literally requires a book to answer. Depends on gazillion of parameters (e.g. RANS or LES?) I would isolate and minimise this question.
In any case, have a review on `grid quality metrics` (e.g. Richardson extrapolation, `grid convergence index` etc.)
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Old   April 14, 2020, 17:29
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Quote:
Originally Posted by HPE View Post
That literally requires a book to answer. Depends on gazillion of parameters (e.g. RANS or LES?) I would isolate and minimise this question.
In any case, have a review on `grid quality metrics` (e.g. Richardson extrapolation, `grid convergence index` etc.)
I'm not using RANS or LES: I'm using a non-turbulence model. Does this help?
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Old   May 12, 2020, 04:34
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you could make grid independence test to see if the mesh is refined enough.
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Old   May 14, 2020, 02:02
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Quote:
Originally Posted by zhaohb11_cfd View Post
you could make grid independence test to see if the mesh is refined enough.
can you elaborate?
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Old   May 14, 2020, 02:14
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Hi

- Please do google the following keywords: 'grid indepence test', 'grid independency', 'Richardson extrapolation' to get the sources.
- In the nutshell, you start with a set of settings and mesh of a spatial-temporal resolution, select a flow quantity, and refine mesh and monitor the flow quantity to see whether increasing spatial or temporal resolution changes the outcome. If no considerable change occurs on the flow quantity by increasing those resolutions, you do then assume that your mesh or setup is grid independent.
- Do changes in isolation, and monitor changes in isolation. Dont change every possible settings at the same time.

Hope makes sense. (was writing on the phone, thus bad quality answer in terms of style)
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