[fds-smv] moving boundary & inclined surface

[chen...@gmail.com]

Hi, Dear FDS developers,

First, thank you all for your excellent work to maintain FDS.
Currently, FDS cannot deal with inclined surface (except by zig-zag
approximations) or moving boundary problems.
In last fire conference, I was told that you guys are planning to
solve this issue by using particle method (or similar mechanism).
Is it possible that FDS has these functions in the near future?

Many thanks and any information is appreciated.

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[rmcdermo]

http://sites.google.com/site/randymcdermott/mcdermott_CFD2010paper.pdf?attredirects=0

Here is a draft of a paper I'm presenting in Lisbon in June. An
inclined surface would be handled by the immersed boundary method. My
hope is that some basic geometries (including an inclined plane) will
be available for beta testing with FDS 6 release (late summer). But I
would suspect that it will be on the order of a year (or more) before
these methods are perfected and robust enough for everyday use.

[Emanuele Gissi]

Randy, that's really amazing.
Thank you very much for the insight.
We look forward to FDS 6.
Emanuele

On 8 Mag, 18:40, rmcdermo <randy.mcderm...@gmail.com> wrote:
> http://sites.google.com/site/randymcdermott/mcdermott_CFD2010paper.pd...

[chen...@gmail.com]

Hi, Randy.

Thanks for you reply.
I read your paper and it is very impressive.
Could you please let me know what technique has been used to describe
the curved interface? (level set or front tracking?)
Has "moving boundary" been implemented too? or in the near future?
Has conjugated heat transfer been implemented?

Sorry for so many questions.
Thanks in advance and any information is appreciated.

On May 8, 12:40 pm, rmcdermo <randy.mcderm...@gmail.com> wrote:
> http://sites.google.com/site/randymcdermott/mcdermott_CFD2010paper.pd...
>

[rmcdermo]

Liguo,

At the moment the surface is well defined and the motion of the
geometry is prescribed. To describe the curved surface for a sphere,
for example, I simply specify a center point and a radius. In the
example in the paper I show a "fastball" moving at 90 mph (Re=200,000)
that is also rotating at 20 revolutions/sec. This does not mean that
the ball his held fixed and the air flows at 90 mph around it; the air
and the ball are both moving at 20 m/s (a relative velocity of 40 m/s
\approx 90 mph). A rough wall log law is prescribed for the velocity
near the surface. So, the answer to your question is that moving
boundaries are possible and have been implemented for my sphere test
case. At present I am working to implement more simple geometries.

Heat transfer has not been added yet. This is the next step after we
have verified the momentum transfer.

We do not have plans to track the geometry with the level set
approach, but it may be possible in the future. Ruddy Mell has
implemented a 2D level set method for tracking a fire line in
wildfires. Eventually we will generalize this to 3D and it will be
available for many different applications (e.g. premixed combustion,
liquid surfaces).

Cheers,
Randy

On May 11, 10:17 am, "chenli...@gmail.com" <chenli...@gmail.com>

[chen...@gmail.com]

Randy, thanks a lot for your answer and your impressive work.
I believe adding heat transfer in the fluid part should be similar,
but conjugated to solid, a little bit tricky.
I am looking forward to the FDS6 release.

Best,
Liguo