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Bubbly flow boundary conditions

Posted February 20, 2013 at 07:58 by beauty

meeting the same problem
Quote:
Originally Posted by Vivek
;99722
Hey Danny,

It is very simple but not straight forward. In many cases you would seen people model the top gas-liquid surface as outlet using two-fluid model. But, I hope that you would agree with me that two-fluid model is not expected to predict the gas-liquid surface. Ypu can model the top gas-liquid interface as follows:

1. Set top surface as inlet. Set all componet of liquid velocity to zero. Set vertical gas velocity to terminal rise
...
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Old

Good news about airfoil and OpenFoam

Posted February 20, 2013 at 03:42 by skeptik (CFD notes)

So, at the end of the testing OpenFOAM/simpleFoam, i get:

NACA23012
U=21.3, Re=0.44e6,

LowRe case, LaunderSharmaKE:
1. OF 1.7 cannot solve the case with kEpsilon on hex+tetra 2D mesh. It just crashes.

2. There are a lots of details when you use LowRe LSkEps model, you need lots of iteration, lots of interpolation data to provide better accuracy.

3. People invented k-omega for different flows near the walls. And better one - kOmega...
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Old

Hey, Dude, be careful with liftDir/dragDir in controlDict

Posted February 19, 2013 at 05:41 by skeptik (CFD notes)

When U is changed due to angle of attack you should change controlDict in libForces section.

So, what can you get when you have proper controlDict

U=56.4, Re=1.6e6

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The mesh was refined so it was OK after checkMesh

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not bad) the next - recalculate LowRe K-eps, just for fun.
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Old

TUI commands for running a Transient simulation in ANSYS FLUENT

Posted February 18, 2013 at 11:22 by diamondx

The TUI command solve/iterate 100 just iterates 100 more iterations. This is used for running steady simulations.

Use the following commands for running a transient simulation:

solve/set/time-step 1e-2 ( for setting the time step size)

solve/dual-time-iterate 100 40 ( 100 is the number of time steps and 40 is the iterations per time steps)
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Old

Hexa dominant meshing

Posted February 11, 2013 at 20:36 by diamondx

Quote:
Originally Posted by PSYMN View Post
Hex Dominant doesn't really play well with the other methods. You will also have a hard time when you try to merge it with the Hexa method, so you will need to do things in the right order...

Hex Dominant is also really more of an FEA method. It starts from the quad surface mesh and grows into the middle. If you don't have a quad surface mesh, it surface meshes everything first and then starts. It doesn't do the material point flood fill that the octree tetra mesher does. It
...
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