Thursday, January 5, 2012

Flow around an egg

My first result: The flow around an egg with diameter 1 and length 1.5 m. I used a very non realistic kinematic viscosity (nu) for this simulation: 0.01 m2/s. The Reynolds number Re=d*u/nu = 1*10/0.01=1000. The kinematic viscosity of air is 15e-6 m2/s. With that kinematic viscosity Re would become ~7e+05. I used the icoFoam solver. At the more realistic higher Reynolds numbers an other solver has to be used.
Flow around an egg. p is the reduced flow pressure/rho.

The egg was modelled in Rhino, exported to a stl file. With the OpenFoam tool snappyHexMesh a mesh was created.

The next figure shows the flow at Re 7e5. At the back side a vortex is visible.

kinematic viscosity of air increased to 15e-6 m2/s, Re~7e5




CFD with OpenFoam

A fine place to download a compiled package for the mac is this page of the ETH of Zurich. The OpenFoam package comes with some limited documentation. Many people have put extra info on the web:

openfoamwiki 
foamcfd
hydroniumion 
dutchopenfoamusers
tutorial
Bence Somogyi
macopenfoam for a prebuilt package for mac
openFoam 2.0 for MAC 0S 10.7 
OpenFoam 2.1 for mac OS 10.6
code saturne on mac
code saturne
literature
J.H. Ferziger & M. Peric "Computational Methods for Fluid Dynamics" (Springer)
To theoretical for me.

Goro Tamai, "The Leading Egde", 1999 Bentley Publishers
Very interesting and readable !