[aravind vashista]

Hii all
I am simulating a simple 2D diffusion flame that is open to the atmosphere. The Computational domain is as shown. It is having following inlet conditions
Air= mass flow inlet
Fuel=mass flow inlet
Burner wall= Wall
Outlet= Pressure outlet
Axis=Axis
and another edge that is open to the atmosphere. What boundary condition should I specify for this edge? Can I specify a pressure outlet or interior, or pressure far field?
I appreciate your valuable time for reading this post and I am hoping to get valuable suggestions
Thank you

[duri]

It is better to reconsider the domain size for better accuracy.

For the given domain, mixing and shear layer would penetrate the boundaries hence outflow has to be a non reflecting boundary condition.

The open to atmosphere can be pressure far field, because pressure outlet would approximate reverse flow in the re-circulation zone near wall. Pressure far field try to force static pressure at boundary which is also not accurate but I think it is better than outlet. Interior won't work at boundary it should be either periodic or symmetry.

[aravind vashista]

Thank you for your response, I will increase my domain size and implement the far-field condition. However, should I give some flow in the axial direction (very low Mach number of the order e-2) or make it zero?