Boundary conditions for open space with wind?

[cesss]

Let's consider the smoke demo, and let's suppose you "cut" the box enclosure in two halves: The half in the bottom has no changes (you have the floor and the four walls), while the half at the top has no ceiling nor walls... just open space.

Now let's suppose you want air to enter from the left at a wind speed of 1m/s in a given direction parallel to the ground (with a constant vector such as u_wind=[uwx,uwy,0]), and also with a Dirichlet constant temperature (call it Twind for example).

Now you want the demo to simulate how the smoke interacts with the wind arriving from the left with its Twind temperature.

How would you specify the boundary conditions for the upper half of the box?

Is there any risk for the system becoming unstable because of the pressure increasing or decreasing a lot because of the wind or because of the air escaping to the open space?

[doyubkim]

Hi @cesss! That should be doable by modifying the boundary condition. The current public API doesn't support it right out of the box, but I think it won't be too hard to have the functionality.

[cesss]

Let me suggest you to implement this feature (fluid simulation with open boundaries and wind), because it would enhance the quality of your smoke demo a lot (currently it doesn't look very realistic because the generated smoke is symmetrical. If you add wind to it, the symmetry would disappear, and it would be much more realistic.