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 sega April 19, 2008 11:32

I have some questions regardin

I have some questions regarding the dam break problem in general.

I want to simulate the basic dam break problem.
It's similar to the one used in the tutorials, but without the barrier.

I have data to compare from experiments (Martin & Moyce, 1951) and two numerical calculations (Griebel et al., 1995 and Ramaswamy, 1987).

The numerical soultions are both caluclatet for different Reynolds-Numbers.
The Reynolds-Number for this problem is known as
Re = H*sqrt(g*H) / nu
Therin H equals the initial High of the water column, g gravity and nu the dynamic vicosity.

And now my first question.
Which dynamic vicosity is meant to play a role in this problem. I suppose it must be the one for the water. So to compare the solutions obtained at a specific Re-Number I can calculate the appropriate nu and define it in OpenFOAM for the water-phase.

Now I have TWO problems left.

1. What Do I with the second nu?
I don't think it's free to chose for the second phase.
2. What about the surface-tension?
I have no idea about what to specify. Is it possible to derive it from the Re-Number? Or from the combination of phases?

 fugu April 19, 2008 16:44

I never got the chance to get

I never got the chance to get the original Martin & Moyce paper... but I read a description of the
experiment somewhere else and I believe they used water and air. Then they just adimensionalized their results.
If I remember correctly the size of the experimental setup was quite big. I believe you can omit surface tension and give it a shot.
Hope this helps

 sega April 20, 2008 09:54

Ok, I used the properties for

Ok, I used the properties for air and water at constant temperature and zero surface tension (sigma).

The movement of the water columns looks familiar.

But to compare it with the experiment there is some post-processing to do.
I have posted my questions in the post-processing-forum:
http://www.cfd-online.com/OpenFOAM_D...tml?1208699365

 sega April 20, 2008 10:03

The experimental data in the o

The experimental data in the original Martin & Moyce is found here:
http://www.jstor.org/sici?sici=0080-4614(19520304)244%3A882%3C325%3APVAESO%3E2.0.CO%3B2-7

I'm able to access the paper trough my university account.

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