[mehrdadmostafavi]

Hello all,

I'm simulating hydrogen leakage from a pipeline to free space, with wind flow from left to right in a steady state. I have the following problems. I would be grateful if anyone could help me.
1- My Geometry is a box with an orifice in the middle of the bottom face of the box as a leakage point. (See attachment)
2 - the boundary conditions are like this:

• Mass flow inlet for the leakage point
• Velocity Inlet for Wind in the left face of the box
• Pressure outlet with the option of "prevent reverse flow." for all the rest faces
• Wall around the leakage point

I activated the species transport, K-e turbulent model, and energy equations.

Problems:

1. I have 3 sample sizes for the leakage point and 4 for the wind speed. I did the mesh independence study for a 1mm leakage size, but the problem is that it doesn't work when I change the leakage size. I tried several mesh types, and the best one was the structured one that I'm using now with the O-grid type for the leakage orifice.
2. Another problem is that I will have water vapor in my answers, which means that the decrease in the H2 concentration is not due to diffusion, but to the consumption of H2 to produce H2O. I want to know what the solution would be for it.
3. When I want to consider the scenario with 0 wind flow rate, the continuity doesn't converge, even if I'll change the wind inlet as an outlet. It seems like hydrogen fills the space, which is unacceptable for free space.

I really appreciate any help you can provide.