[JohnEFM]

Hello,


I am trying to set up a 2D simulation of a swirl burner using a thin slab from the original geometry. To set up my simulation, I would like to add a swirl component for an inlet boundary condition, specifically for the air inlet boundary. Some specifications of my simulation are: it's time-based, and it uses a transient solver, a spray model for the injector, a SAGE combustion model, a LES dynamic structure turbulence model, and a source model for ignition. Does anyone know a way to add a swirl component for an inlet boundary condition?


Thank you

[Yaju]

Hi,

Unless there is a problem with my understanding of your simulation, this simulation would not be possible in two-dimensions.

Swirl burners will have a 3D flow structure to them. Something like rotating in a plane and then translating along the plane normal.

If the purpose of running in 2D is to save computational time, then I would suggest you to run a periodic case.

I hope this helps.

[JohnEFM]

Originally Posted by Yaju

Hi,

Unless there is a problem with my understanding of your simulation, this simulation would not be possible in two-dimensions.

Swirl burners will have a 3D flow structure to them. Something like rotating in a plane and then translating along the plane normal.

If the purpose of running in 2D is to save computational time, then I would like you to suggest running a periodic case.

I hope this helps.

Hi,


I apologize for the miscommunication, my PI used an imprecise language when he explained it to me before posting my question. I am trying to run a simulation using a thin wedge that might approximate 2D to save computational time. How would you suggest that I set it up in a periodic case?


Thank you.

[Yaju]

Hi,

You can refer to one of our engine sector example cases in CONVERGE Studio (File->Load example case -> Internal combustion engines -> Heavy duty diesel) for setting up a periodic case. You will need to make the side/cut surfaces of your wedge as periodic boundaries. Please refer to the boundary setup to see how to define the periodic boundaries.

If you are a new user. I will recommend you to attend our online training using your universities credentials (https://convergecfd.com/training). These training sessions are free.

[nvandam]

Hi,


I am John's academic advisor and working with him on this problem.

You can refer to one of our engine sector example cases in CONVERGE Studio (File->Load example case -> Internal combustion engines -> Heavy duty diesel) for setting up a periodic case.

The question is not how to set up the periodic boundaries, which we've already done, the question is we have an air inlet at one end (and outlet at the other), but we want the inlet air velocity to have a swirl, i.e. tangential, component. The diesel case you suggest does not have any inlets (or outlets), and so unfortunately won't help with this particular problem. A better analogy would be to the Sandia Flame D cases, if the Pilot inlet had a swirl component (Jet inlet is still normal to the inlet surface).


Looking at that example it appears the Pilot inlet uses a file to define the inlet velocity, and the profile type says spatial rather than temporal, so it would seem to be specifying a velocity profile as a function of position. The Flame D case has no swirl, but it would seem we could use this approach to add a swirl component to our inlet, assuming I am interpreting the given information correctly. The coordinate system will still always be cartesian, correct? Our velocity components would be constant in cylindrical coordinates, but I don't see any option to use a cylindrical coordinate system to specify the velocity coordinates.


Prof. Van Dam

[Yaju]

Hi,

As you mentioned, a spatial file can be used to specify the swirl inlet flow conditions. The spatial location and velocity components all have to be specified in the cartesian co-ordinate system. So, you will have to modify the velocity from cylindrical to cartesian system.