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kingfaycel5 February 27, 2013 03:59

help needed with simulation of turbulent flow around an obstacle with openfoam
I am a new user of OpenFoam, and very intersted in it. However, it is difficult for me to learn it only by its User Guide and Programing Guide. I tried to understand its codes, and I found that it is not a easy job due to limited remark. Can someone give some suggestion? i want find soman work someone work in this :

simulation of turbulent flow around an obstacle with openfoam

Thanks in advance![/QUOTE]

fumiya March 1, 2013 12:35

Hi kingfaycel5,

I understand OpenFOAM is difficult for beginners including me, but
you will be able to get a better grasp of OpenFOAM through trial
and error. If you have more specific questions in this process, ask
them and you will get more answers:)

At First try the tutorials and understand how to use OpenFOAM.
If you search the Internet, you can find the many threads and
documents related to your interest:

Best wishes,

chegdan March 1, 2013 16:36

Zergui, welcome to the forum.

Just to add on top of what Fumiya stated. Learning OpenFOAM can be daunting, but we all started somewhere. I will refer to a recent post by Wyldckat for some inspiration on starting to learn OpenFOAM. Here is a list of places to start:

For things specific (e.g. meshing), there are wiki entries and presentations similar to:

This is similar for other features in OpenFOAM, like linear system solvers, combustion modeling, adding scalars to icoFoam and using GUI pre processors. There are also training lectures at the old workshops e.g.7th and 6th workshop.

Some general comments about learning:
  • i would start with learning the workflow of how one would go about solving a problem in openFOAM i.e. the process of pre-processing -> solving -> post-processing. How do you draw your geometry? how do you mesh? what is fvSchemes? how do I do basic things in paraview? etc.
  • Peruse the utilities and search the forum or google what a utility does if the name or description sounds like you might use it.
  • look through this thesis and these. They are tremendously helpful in learning finite volume and how the schemes work in OpenFOAM
  • break down what you want to model in general terms e.g. steady-state isothermal incompressible momentum transport for turbulent flow...use simpleFoam. I know this by googleing and also by going through the solver and reading the general descriptions of each one.

These are just a few thoughts on the subject, but in general one needs to get in there and just try different solvers. It takes time to learn the code and you will learn more by gaining experience (i.e. making mistakes). My only significant tip to you is to balance and also spend time to research questions. People that tend to post 500 messages in 4 months, attach "please help" or "urgent" to posts, and/or not be patient with the community tend to get less help. I have questions that have never been answered, ones that I have gone back and answered myself, and other times i have questions that are answered within 20 expect somewhere in between :D . Good luck!

JR22 March 3, 2013 01:21

Learn by using one of the GUIs out there
Search in this forum for OpenFOAM GUIs. Some of them are geared for external aerodynamics. From your description of "flow around an obstacle", you might be talking about "external aerodynamics" (search this forum for those keywords too). Use the GUIs, then go to the files they create and try to match what you did to what is written in them.

Here is a washlist of some of them (Open Source):
- Helyx-OS
- Engrid
- Discretizer
- CMeshFoil

Try to do as much as you can within Linux. If you have a Windows machine, then install a VirtualBox with Linux as guest. You might also try to look at CAElinux that has OpenFoam and other tools.

Go into Youtube and look for OpenFoam tutorial. You will find videos step by step on how to run the tutorials that come with OpenFoam.

RocketMan1691 March 3, 2013 16:07

Sources of Geometry
Having recently travelled a very similar path to that shown in this thread, the previous entries in this thread struck a very strong chord.

I am still very much a learner on OF itself but I had the following thoughts on how to generate geometry.

2-D is probably something that can be handled relatively easily. 3-D is much more challenging. Many awesome commercial packages for surface and solid modelling exist but all are very expenisive. However, I tend to use a product called Blender that is open source. The learning curve is quite steep but there is a huge amount of help. If you can imagine something, Blender can model it.

The resulting model can be output in an STL file, at whatever level of refinement is needed, ready for meshing.

But meshing is a completely different story

Hope that is of help

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